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Publication date: Available online 26 May 2022
Source: Computers & Fluids
Author(s): Tong Zhou, Haitao Dong
Publication date: Available online 25 May 2022
Source: Computers & Fluids
Author(s): Francisco Lozano, Iman Rahbari, Guang Lin, Guillermo Paniagua
Publication date: 15 June 2022
Source: Computers & Fluids, Volume 241
Author(s): Ming Pan, Yuhong Dong, Quan Zhou, Lian Shen
Publication date: 15 June 2022
Source: Computers & Fluids, Volume 241
Author(s): Th. Skamagkis, E.M. Papoutsis-Kiachagias, K.C. Giannakoglou
Publication date: 15 June 2022
Source: Computers & Fluids, Volume 241
Author(s): Xiaofeng He, Kun Wang, Yiwei Feng, Lili Lv, Tiegang Liu
Publication date: Available online 25 May 2022
Source: Computers & Fluids
Author(s): Jijian Lian, Xiuwei Yang, Bin Ma, Wenjuan Gou
Publication date: Available online 24 May 2022
Source: Computers & Fluids
Author(s): Gustaaf B Jacobs, Jose Castillo
Publication date: Available online 4 May 2022
Source: Computers & Fluids
Author(s): Hui Xu, Guohua Tu, Spencer J. Sherwin
Publication date: Available online 21 May 2022
Source: Computers & Fluids
Author(s): Luciano K. Araki, Rafael B. de R. Borges, Nicholas Dicati P. da Silva, Chi-Wang Shu
Publication date: Available online 21 May 2022
Source: Computers & Fluids
Author(s): Yuhang Wang, Liang Pan
In this study, we present a robust conservative time-staggered scheme for variable density flow. This pressure correction scheme uses the compressible Navier-Stokes equations and is implemented in the collocated finite-volume open-source computational fluid dynamics solver code_saturne. The Helmholtz equation is solved for the pressure increment, taking the thermodynamic pressure into account and avoiding the acoustic time step limitation. The internal energy equation is used and completed by a source term derived from the discrete kinetic energy equation, thus enforcing total energy conservation and consistency for irregular solutions. A numerical analysis providing conditions ensuring the positivity of the thermodynamic variables is proposed. The scheme is verified and validated against analytical and experimental test cases. Its ability to reproduce the pressure variation while conserving the mass is demonstrated. Its conservative property and time convergence order are also verified. An irregular shock solution is studied, emphasising the importance of the source term in the internal energy equation. Finally, the scheme is validated against reference numerical results on a two-dimensional natural convection cavity and experimental data on a three-dimensional ventilation test case. The comparison against experimental data is made using first-and second-order turbulent simulations.
This work explores the development and the analysis of an efficient reduced order model for the study of a bifurcating phenomenon, known as the Coandă effect, in a multi-physics setting involving fluid and solid media. The latter is governed by the Navier-Stokes equations for an incompressible, steady and viscous fluid and by the elasticity constitutive relations modelling the behaviour of the solid. Taking into consideration a Fluid-Structure Interaction problem, we aim at generalizing previous works towards a more reliable description of the physics involved. In particular, we provide several insights on how the introduction of an elastic structure influences the bifurcating behaviour. We have addressed the computational burden by developing a reduced order branch-wise algorithm based on a monolithic Proper Orthogonal Decomposition. We compared different constitutive relations for the solid, and we observed that a nonlinear hyper-elastic law delays the bifurcation w.r.t. the standard model, while the same effect is even magnified when considering linear elastic solid.
In the present work, we present a new version of the pressure-based Implicit Potential (IPOT) method for incompressible flows, which can be applied on a fully collocated mesh. The new version combines the IPOT algorithm with the Rhie and Chow (RC) technique, to produce solutions on collocated grids that are free of spurious pressure modes. The IPOT-RC method retains all the benefits of the original algorithm, i.e. explicit velocity-pressure coupling, easy implementation and reduced iteration time, without requiring a special grid topology. The presentation of the IPOT-RC method, is accompanied by an extensive discussion on the cause of the spurious oscillations in zero-div problems in general, and a possible cure that is linked to the Rhie and Chow technique. The IPOT-RC method is validated through several benchmark problems including the lid-driven cavity flow, flow over a backward facing step and Direct Numerical Simulation (DNS) of turbulent channel flow.
We propose an accurate and robust solver for the incompressible Navier–Stokes equations. The method is based on a DG spatial discretization and on the TR-BDF2 method for time discretization and its superior efficiency with respect to other widely used implicit approaches has been shown in a number of classical benchmarks. Good scaling properties of the parallel implementation in the framework of the deal.II software package, as well as accurate simulations in complex geometries, are presented, making the proposed solver attractive also for large scale industrial applications.
We propose an efficient, accurate, and robust implicit solver for the incompressible Navier–Stokes equations, based on a DG spatial discretization and on the TR-BDF2 method for time discretization. The effectiveness of the method is demonstrated in a number of classical benchmarks, which highlight its superior efficiency with respect to other widely used implicit approaches. The parallel implementation of the proposed method in the framework of the deal.II software package allows for accurate and efficient adaptive simulations in complex geometries, which makes the proposed solver attractive for large scale industrial applications.
In this paper, we developed a hybrid volume of fluid (VOF) and level set interface capturing scheme with quartic surface representation for unstructured meshes. The so-called {THINC-scaling scheme with quartic surface representation (THINC-scaling/QSR)} preserves the merits of the mass/volume conservativeness from the VOF scheme along with the geometric faithfulness from the level set scheme. Compared with linear/quadratic surface representation used in many other interface capturing schemes, the fluid interface is defined more precisely as a quartic polynomial surface of THINC function which synchronize the interface between the VOF and level set function in a straightforward solution procedure. We update the VOF function using a finite volume formulation. The level set function is first locally updated via a semi-Lagrangian method for interface cells and then reinitialized within each time step. Two-dimensional algorithm has been developed and verified by some benchmark tests on unstructured meshes. Convincing evidence suggests that the present scheme, with quartic surface representation, can provide high-fidelity solution with more pronounced sub-grid interface capturing capability than other most advanced methods.
In this article, a new numerical model is proposed to detect numerically the Hopf bifurcation point of incompressible fluid flows problems. The concept of this model consists to propose a Hopf bifurcation indicator which is solved by a high order mesh free algorithm (HO-MFA) using the moving least squares (MLS) approximation. This numerical model is based on a strong formulation of Navier–Stokes equations. This procedure allowed us to recover the results of the literature in 3D using only a 2D modelization.
In this article, a new numerical model is proposed to detect numerically the Hopf bifurcation point of incompressible fluid flows problems. The concept of this model consists to propose a Hopf bifurcation indicator which is solved by a high order mesh free algorithm (HO-MFA) using the moving least squares (MLS) approximation. This numerical model is based on a strong formulation of Navier–Stokes equations. This procedure allowed us to recover the results of the literature in 3D$$ 3D $$ using only a 2D$$ 2D $$ modelization for low Reynolds number. This new model is tested on the classical flow around a cylindrical obstacle and the backward-facing step flow to show the advantage and ability of the proposed model to detect the bifurcation points and to determinate the flow periodicity.
A novel dynamic adaptive unstructured mesh (DAUM) algorithm is proposed to solve incompressible multi-object relative motion (MORM). The DAUM algorithm, consisting of exponential function deformation, adaptive edge swapping, and area Laplace smoothing, can greatly improve dynamic mesh robustness and perfectly overcome mesh skewness. The core of DAUM is the adaptive edge swapping inspired by Delaunay triangulation, which is distinguished from traditional edge swapping. The adaptive edge swapping can fully consider the relationship of neighbor elements only using Delaunay triangulation. Meanwhile, the implementation and reliability of adaptive edge swapping are better than the traditional edge swapping method due to eliminating the interference of the non-convex polygon, so more code remedies can be avoided. Using the DAUM, none of the vertices is inserted or deleted so that the manipulation of the dynamic mesh is easily implemented and maintains computational efficiency in the process of mesh motion. Three representative geometries are used to assess the performance of the DAUM in MORM. To systematically analyze the advantages of DAUM, two relatively moving cylinders have been numerically investigated in incompressible flow. The inline force and lift force profiles on two cylinders are obtained and analyzed by using the flow field information. Three interaction stages are divided based on the parameter G and the interactional intensity of two inner anticlockwise vortices is considered as the division criteria. At the running process of the DAUM algorithm, the dynamic mesh quality is well controlled and remains in the high-quality range based on the aspect ratio (AR) criterion. The results indicate that the proposed DAUM algorithm can properly solve the difficulties caused by MORM, especially for period oscillation motion.
We have generalized a Lagrange multiplier based fictitious domain (DLM/FD) method to simulating the motion of neutrally buoyant particles of non-symmetric shape in non-Newtonian shear-thinning fluids. For a self-propelled swimmer formed by two different size disks, the effect of shear-thinning makes the swimmer moving faster in the direction of larger disk and decreases the critical Reynolds number (for the moving direction changing to the opposite one) when decreasing the value of the power index n in the Carreau-Bird model.
In this article we discuss the generalization of a Lagrange multiplier based fictitious domain (DLM/FD) method to simulating the motion of neutrally buoyant particles of non-symmetric shape in non-Newtonian shear-thinning fluids. Numerical solutions of steady Poiseuille flow of non-Newtonian shear-thinning fluids are compared with the exact solutions in a two-dimensional channel. Concerning a self-propelled swimmer formed by two disks, the effect of shear-thinning makes the swimmer moving faster and decreases the critical Reynolds number (for the moving direction changing to the opposite one) when decreasing the value of the power index n in the Carreau-Bird model.
(i) The ISPH-FVM method has higher computational efficiency than the pure SPH particle method. (ii) Two-phase interface can be well captured by the ISPH-FVM coupling algorithm. (iii) The ISPH-FVM coupling method can accurately calculate the flow field variables, while overcoming the complexity of pure particle method to deal with the inflow/outflow boundary.
Two-phase flow involves complex interface evolution process such as the formation, development, pulsation, and rupture of phase interfaces. Numerical simulation is one of the important means to study two-phase flow. The tracking and reconstruction of phase interface is the focus of two-phase flow simulation. A two-phase flow simulation algorithm based on coupled incompressible smoothed particle hydrodynamics (ISPH) method and finite volume method (FVM) is developed in this article. In present ISPH-FVM coupling algorithm, one phase which has smaller volume is represented by SPH particles, while the other phase is defined on the FVM grids. The coupling of ISPH and FVM is achieved through the transfer and interaction of physical parameters at the overlapping area of the SPH particles and FVM grids. The continuous medium surface force model is also introduced into the ISPH-FVM coupling algorithm to study the effect of surface tension on the two-phase flow. Several numerical examples of two-phase flow are adopted to verify the effectiveness of the ISPH-FVM coupling method.
We solve the unsteady Stokes problems by using the physics informed neural networks coupled with small sample learning, and give the proofs to guarantee the convergence of the neural networks as well as the convergence of the loss function. Moreover, we combine the model-driven (the differential forms of the neural networks) and the data-driven (the numerical data) to construct the loss function and enhance the efficiency as well as the accuracy of the method. Furthermore, this method is meshfree and can simultaneously solve each variable of the equations separately in parallel framework.
In this article, we develop the physics informed neural networks (PINNs) coupled with small sample learning for solving the transient Stokes equations. Specifically, the governing equations are encoded into the networks to construct the loss function, which involves the residual of differential equations, the initial/boundary conditions, and the residual of a handful of observations. The approximate solution was obtained by optimizing the loss function. Few sample data can rectify the network effectively and improve predictive accuracy. Moreover, the method can simultaneously solve each variable of the equations separately in a parallel framework. The information of the numerical data is compiled into the networks to enhance efficiency and accuracy in practice. Therefore, this method is a meshfree and fusion method that combined data-driven with model-driven. Inspired by the Galerkin method, the paper proves the convergence of the loss function and the capability of neural networks. Furthermore, numerical experiments are performed and discussed to demonstrate the performance of the method.
Publication date: 15 August 2022
Source: Journal of Computational Physics, Volume 463
Author(s): Mingyang Cheng, Lingyan Tang, Yaming Chen, Songhe Song
Publication date: 15 August 2022
Source: Journal of Computational Physics, Volume 463
Author(s): Jan Nordström, Andrew R. Winters
Publication date: 15 August 2022
Source: Journal of Computational Physics, Volume 463
Author(s): Wenjing Feng, Hui Guo, Yue Kang, Yang Yang
Publication date: 15 August 2022
Source: Journal of Computational Physics, Volume 463
Author(s): Daniel Zhengyu Huang, Tapio Schneider, Andrew M. Stuart
Publication date: 15 August 2022
Source: Journal of Computational Physics, Volume 463
Author(s): Francesco Magaletti, Mirko Gallo, Sergio P. Perez, José A. Carrillo, Serafim Kalliadasis
Publication date: 15 August 2022
Source: Journal of Computational Physics, Volume 463
Author(s): V.M. Goloviznin, Pavel A. Maiorov, Petr A. Maiorov, A.V. Solovjev
Publication date: 15 August 2022
Source: Journal of Computational Physics, Volume 463
Author(s): Sifan Long, Xiaokang Fan, Chao Li, Yi Liu, Sijiang Fan, Xiao-Wei Guo, Canqun Yang
Publication date: 15 August 2022
Source: Journal of Computational Physics, Volume 463
Author(s): J. Karátson
Publication date: 15 August 2022
Source: Journal of Computational Physics, Volume 463
Author(s): Brian A. Freno, Brian R. Carnes, Victor E. Brunini, Neil R. Matula
Publication date: 15 August 2022
Source: Journal of Computational Physics, Volume 463
Author(s): Guanlan Huang, Yulong Xing, Tao Xiong
A compressible boundary-layer flow over a flat plate with sharp leading edge is studied in the hypersonic limit. The interaction between the shock wave and boundary layer is characterized using the hypersonic interaction parameter \(\chi = M_{\infty }^3\sqrt{C/\mathrm{Re}_{\infty }}\) where \(M_{\infty }\) and \(\mathrm{Re}_{\infty }\) are the free-stream Mach and Reynolds numbers, respectively, and C is the Chapman–Rubesin constant. The flow is studied for Prandtl number \(\mathrm{Pr}=1\) using a shock-layer analysis of the equations of motion governing high-speed compressible flow. In the strong interaction limit the value for \(\chi \) approaches infinity, \(\chi \rightarrow \infty \) , and there exists coupling between the shock wave and boundary layer that extends the plate length. For finite interaction, \(1< \chi < \infty \) , there is coupling between the shock wave and boundary layer that can extend well-beyond the plate’s leading edge. To study this transition, from \(\chi \sim O\) (1) to \(\chi \gg 1\) , we solved the Prandtl boundary-layer equations that represent the viscous-layer flow (Region I) at non-adiabatic wall conditions using a standard line relaxation method. For the inviscid layer (Region II), we reduced the governing thin inviscid-layer equations to ordinary differential equations by using the method of characteristics. We then matched values for flow variables of similar order computed in the viscous-(Region I) and inviscid-(Region II) layers at the boundary-layer’s edge by using a minimization algorithm. Thus, solutions produced using the technique, denoted asymptotic matching Technique A, required only a single streamwise sweep to achieve convergence between these flow variables computed in the viscous and inviscid layers and matched at the boundary-layer edge. Solutions for flow variables found using Technique A are then compared with solutions for similar \(\chi \) and wall enthalpy values found using a separate shock-layer analysis, denoted matching Technique B, that utilized a tangent-wedge approximation for the inviscid layer. Technique B required successive streamwise sweeps such that initial pressure conditions upstream and downstream are both satisfied at each sweep. The converged solution was obtained during the final sweep based on a preset convergence criteria. Shock-wave and boundary-layer profiles; wall pressure and shear stress computed using both Techniques A and B are compared with values computed using computational fluid dynamics (CFD). The results show good agreement.
This work presents a robust method that minimises the impact of user-selected parameter on the identification of generic models to study the coherent dynamics in turbulent flows. The objective is to gain insight into the flow dynamics from a data-driven reduced order model (ROM) that is developed from measurement data of the respective flow. For an efficient separation of the coherent dynamics, spectral proper orthogonal decomposition (SPOD) is used, projecting the flow field onto a low-dimensional subspace, so that the dominating dynamics can be represented with a minimal number of modes. A function library is defined using polynomial combinations of the temporal modal coefficients to describe the flow dynamics with a system of nonlinear ordinary differential equations. The most important library functions are identified in a two-stage cross-validation procedure (conservative and restrictive sparsification) and combined in the final model. In the first stage, the process uses a simple approximation of the derivative to match the model with the data. This stage delivers a reduced set of possible library function candidates for the model. In the second, more complex stage, the model of the entire flow is integrated over a short time and compared with the progression of the measured data. This restrictive stage allows a robust identification of nonlinearities and modal interactions in the data and their representation in the model. The method is demonstrated using data from particle image velocimetry (PIV) measurements of a circular cylinder undergoing vortex-induced vibration (VIV) at \(\mathrm{Re}=4000\) . It delivers a reduced order model that reproduces the average dynamics of the flow and reveals the interaction of coexisting flow dynamics by the model structure.
Understanding the dynamics of a water droplet after impacting on a moving wall is significant for many applications such as repelling rain droplets from a vehicle. In this paper, a water droplet impacting on a moving hydrophobic wall is studied numerically using a 3D lattice Boltzmann method (LBM). The accuracy of the present model is validated by comparing with existing correlation equations for the maximum spread factor and the contact time. It is found that the droplet spreads into an asymmetric shape after impacting on the moving wall owing to the momentum transfer from the wall to the droplet. The droplet deformation increases with the increasing of the wall velocity. Because of different bouncing behaviors of the droplet, the effect of the wall velocity on the droplet contact time varies with contact angles: the droplet contact time decreases with the increasing of the wall velocity for θ = 156°, while the droplet contact time increases with the increasing of the wall velocity for θ = 130°. It is also found that the droplet bouncing motion will be suppressed at a high wall velocity for θ = 130°. Finally, a map in terms of the Weber (We) number versus the contact angle (θ) is obtained, showing that a larger critical contact angle is required for droplet rebounding from a moving wall. This work provides a guidance that a moving wall needs to be more hydrophobic than a stationary wall to repel water droplets.
We consider estimation and control of the cylinder wake at low Reynolds numbers. A particular focus is on the development of efficient numerical algorithms to design optimal linear feedback controllers when there are many inputs (disturbances applied everywhere) and many outputs (perturbations measured everywhere). We propose a resolvent-based iterative algorithm to perform (i) optimal estimation of the flow using a limited number of sensors, and (ii) optimal control of the flow when the entire flow is known but only a limited number of actuators are available for control. The method takes advantage of the low-rank characteristics of the cylinder wake and provides full-dimensional solutions by implementing a terminal reduction technique based on resolvent analysis. Optimal feedback controllers are also obtained by combining the solutions of the estimation and control problems. We show that the performance of the estimators and controllers converges to the true global optima, indicating that the important physical mechanisms for estimation and control are of low rank.
This paper investigates the problem of electrophoretic motion of a polyelectrolyte capsule with a porous arbitrary charged conducting shell in an electrolyte (of the same type as the one inside the capsule’s cavity) under the action of an external electric field. The corresponding boundary value problem for the velocity components and pressure in the case of small electrical potentials is analytically solved in quadratures. The solution is analyzed numerically for different values of the specific permeability of the capsule, and the thickness of the porous and the electric double layers. The minimum of electrophoretic velocity dependence on the inverse permeability of the porous layer has been found. It is shown that the electrophoretic mobility decreases upon decrease in the conductivity of the material constituting the porous layer. This means that a dielectric capsule can be used for electrophoresis as well. Moreover, its velocity will be even greater than that of a conducting capsule, all other conditions being equal.
Hypersonic boundary-layer flows over a circular cone at a moderate yaw angle can support strong crossflow instability away from the windward and leeward rays on the plane of symmetry. Due to the more efficient excitation of stationary crossflow vortices by surface roughness, a possible path to transition in such flows corresponds to rapid amplification of the high-frequency instabilities sustained in the presence of finite amplitude stationary crossflow vortices. This paper presents a computational analysis of crossflow instability over a 7-degree half-angle, yawed circular cone in a Mach 6 free stream. Specifically, the nonlinear evolution of an azimuthally localized crossflow vortex pattern and the linear amplification characteristics of high-frequency instabilities evolving in the presence of that pattern are described for the first time. Focusing on the azimuthally compact vortex pattern allows us to overcome significant limitations of the prior secondary instability analyses of azimuthally inhomogeneous boundary layer flows. A comparison between plane-marching parabolized stability equations and direct numerical simulations (DNS) reveals favorable agreement in regard to mode shapes, most amplified disturbance frequencies, and the N-factor evolution. In contrast, the quasiparallel predictions are found to result in a severe underprediction of the N-factors. The most amplified high-frequency instabilities are found to originate from Mack’s second mode waves sustained within the upstream region of nearly unperturbed, quasi-homogeneous boundary layer.
The nonlinear development of Görtler instability over a concave surface gives rise to a highly distorted inflectional flow field in the boundary layer that exhibits strong velocity gradients in the spanwise direction as well as in the wall-normal direction. Such a flow field is susceptible to strong, high frequency secondary instability that can lead to the onset of transition. The present numerical study uses direct numerical simulations and linear secondary instability theory to investigate finite amplitude Görtler vortices and their secondary instability characteristics, respectively, in a hypersonic flow over an axisymmetric cone with a concave aft body. The Görtler modes are excited via azimuthally periodic deformations of the surface geometry and, hence, are fully realizable. For sufficiently small initial amplitudes, the computed growth of the roughness- induced Görtler vortices is shown to agree with the predictions of optimal growth theory. Earlier work on nonlinear Görtler vortices had focused on vortex structures with intermediate amplitudes that resembled bell shaped structures, unlike the mushroom structures with thin stems encountered in lower speed flows. The present results corroborate the findings of other recent studies that fully developed mushroom structures can also exist in the hypersonic regime when the Görtler vortex amplitude is sufficiently large. Computations also reveal that the dominant modes of secondary instability correspond to an antisymmetric “stem” mode associated with the strong, nearly wall-normal shear layers bounding the stem underneath the mushroom structure. The dominant stem modes have supersonic phase velocities, resulting in acoustic radiation to the flow just outside of the boundary layer. To our knowledge, this is the first work documenting the existence of supersonic secondary instabilities in the context of stationary Görtler modes.
A high-fidelity simulation of the massively separated shock/transitional boundary layer interaction caused by a 15-degrees axisymmetrical compression ramp is performed at a free stream Mach number of 6 and a transitional Reynolds number. The chosen configuration yields a strongly multiscale dynamics of the flow as the separated region oscillates at low-frequency, and high-frequency transitional instabilities are triggered by the injection of a generic noise at the inlet of the simulation. The simulation is post-processed using Proper Orthogonal Decomposition to extract the large scale low-frequency dynamics of the recirculation region. The bubble dynamics from the simulation is then compared to the results of a global linear stability analysis about the mean flow. A critical interpretation of the eigenspectrum of the linearized Navier–Stokes operator is presented. The recirculation region dynamics is found to be dominated by two coexisting modes, a quasi-steady one that expresses itself mainly in the reattachment region and that is caused by the interaction of two self-sustained instabilities, and an unsteady one linked with the separation shock-wave and the mixing layer. The unsteady mode is driven by a feedback loop in the recirculation region, which may also be relevant for other unsteady shock-motion already documented for shock-wave/turbulent boundary layer interaction. The impact of the large-scale dynamics on the transitional one is then assessed through the numerical filtering of those low wavenumber modes; they are found to have no impact on the transitional dynamics.
Accurate prediction of aerothermal surface loading is of paramount importance for the design of high-speed flight vehicles. In this work, we consider the numerical solution of hypersonic flow over a double-finned geometry, representative of the inlet of an air-breathing flight vehicle, characterized by three-dimensional intersecting shock-wave/turbulent boundary layer interaction at Mach 8.3. High Reynolds numbers ( \(Re_L \approx 11.6 \times 10^6\) based on free-stream conditions) and the presence of cold walls ( \(T_w/T_\circ \approx 0.26\) ) leading to large near-wall temperature gradients necessitate the use of wall-modeled large eddy simulation (WMLES) in order to make calculations computationally tractable. The comparison of the WMLES results with experimental measurements shows good agreement in the time-averaged surface heat flux and wall pressure distributions, and the WMLES predictions show reduced errors with respect to the experimental measurements than prior RANS calculations. The favorable comparisons are obtained using a standard LES wall model based on equilibrium boundary layer approximations despite the presence of numerous non-equilibrium conditions including three-dimensionality in the mean, shock/boundary layer interactions, and flow separation. We demonstrate that the use of semi-local eddy viscosity scaling (in lieu of the commonly used van Driest scaling) in the LES wall model is necessary to accurately predict the surface pressure loading and heat fluxes.
With an interest in developing and studying the stability of laminar undisturbed basic-state solutions, this work is focused on accurately modeling the laminar flowfield of the boundary layer transition (BOLT) geometry under nominal and off-nominal conditions (i.e., nonzero angles of pitch and yaw). The BOLT flowfield is studied using the DPLR flow solver with MUSCL Steger–Warming fluxes using a set of five grids at different resolutions and identical grid topologies. A total of three different sets of conditions are studied: two flight conditions and one wind-tunnel-scale (33%) condition. (1) For the two sets of nominal flight operating conditions, it is found that the flow structures in the centerline region of BOLT are similar to those found in prior studies including in shape, location, and extent both vertically and spanwise, but a detailed comparison of velocity contours shows that further quantitative convergence studies are warranted. The centerline region, however, extends to at most 4 cm in semi-span at the aft end of the geometry (20% of the semi-span). Away from the centerline and where wind-tunnel-scale results have observed regions of possibly transitional behavior, the laminar flowfield converges with high accuracy. (2) For nominal wind-tunnel operating conditions, all grid resolutions simulated show good agreement in most regions as compared with prior results, with any differences falling within the scatter of existing experimental and DNS results. Aside from this focus, boundary-layer stability is examined outboard of the centerline region at nonzero pitch and yaw for a flight case, and second mode and stationary crossflow instabilities are considered. Second-mode instability is found to be locally significant at certain pitch and yaw angles particularly downstream of the swept leading edges. In addition, stationary crossflow is found to become highly amplified in significant wedges extending to the aft end of the BOLT geometry, with N-factors consistent with those found for HIFiRE-5b associated with transitional flow. The reasons for amplification of these different instabilities are also investigated from a physics-based perspective.
