Poland, June 27, 2019

The course introduces several advanced turbulence modeling topics.
First one refers to the strengths and limitations of the RANS
modeling. This is followed by the discussion of the Large Eddy
Simulation (LES) with strong focus on the evaluation of the quality of
the results. Finally, the laminar-to-turbulent transition models
(including those present in the commercial solvers) are discussed. As
a bonus, the lattice Boltzmann method with the implicit-LES model is
introduced.

Description:

 

This 2-day course is intended for engineers whose work  

concerns CFD modelling of turbulent flows and convective  

heat transfer. The course aims to imbue the participants  

with a thorough understanding of eddy-viscosity based  

RANS models, RANS-based laminar-to-turbulent transition  

models, and LES approaches. A detailed explanation of  

RANS-based techniques will be given with emphasis on the  

interpretation of the results. Limitations and advantages  

of RANS-based strategies will be discussed. An  

explanation of the influence of inlet boundary conditions  

for modelled scalars will be provided; cases in which  

RANS models exhibit a strong sensitivity to the  

prescribed inlet values of the modelled variables will be  

reviewed. 

 

The second part of the course is meant to address the  

deficiencies of RANS models. Examples of applications of  

the Large Eddy Simulation (implicit LES or quasi-Direct  

Numerical Simulation, DNS) and the increasingly popular  

lattice Boltzmann methods will be given. We will provide  

the theoretical background and discuss applications of  

LES for massively separated flows, where the use of  

standard RANS models might lead to significant errors. We  

will teach how to evaluate the quality of a LES solution  

using two-point and autocorrelations and how to estimate  

the required mesh cell and time step sizes to resolve the  

turbulence statistics with sufficient accuracy. 

 

The last part of the course will focus on modelling the  

laminar-to-turbulent transition of a flow. We will  

explain the physics of natural, bypass, and separated  

flow transitions and describe the most popular transition  

models (available in many commercial CFD packages).  

Finally, we will show and discuss the results of  

transition simulations and compare them with experiments,  

DNS, and results obtained using fully-turbulent RANS  

models. 

 

The lectures will consist of theoretical background on  

each of the topics and will be illustrated with  

simulation results. Limitations and advantages of various  

turbulence modelling and convective heat transfer  

modelling strategies will be discussed. It will be  

demonstrated how to overcome or mitigate turbulent flow  

and heat transfer modelling errors by proper selection of  

closure strategies. 

 

The lecturer of the course is Dr Sławomir Kubacki (Dr- 

habil.), a former co-worker of Dr Florian Menter, and an  

author of the laminar-to-turbulent transition models for  

turbomachniery flows.