[philem]

Henning, thanks! I am new to OpenFOAM source code. Could you please explain why there are two sets of RK4values (RK4values and RK4values2)?

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Plz ignore this question. I've found the classical 4th RK in Jameson's paper.

[Andy_bm]

Thank you for your code.

I have been working with rhoCentralFoam solver several years. And I have some problem. Does anyone has the follow problem: rhocentralFoam is good working in 3d cases, BUT only with UPWIND reconstruct scheme? If I change to vanleer scheme or other(gamma, superbee) the solver crashed. Also I tried different grad scheme but it has no result. This problem is present in all my tasks: external flow at M~2-4 or jet stream from nozzle.

Thanks.

[emjay]

Hallo,

i have/had the same problem. Does anybody know the discretization settings for a second order in time and space?

with "backward" the solver crashes, and Euler is only first order and for my unsteady problem to diffusive.

and for spatial dissertation is the same problem, only "upwind" works, any other higher order discretization with limiter function produces overshoots, when i compare the numerical with the analytical solution.

[Eric Brant]

Hi Henning,

I am quite interested in your rhoCentralFoamRK4 and how about the results compared to rhoCentralFoam? Have you ever calculated some cases and compared with other results obtained by FLUNET etc.

Best
Eric

[usv001]

Hello everyone,

I am trying to implement RK4 for rhoCentralFoam as well. I want to clarify a couple of issues pertaining to Henning86's implementation first.

1. Can RK4 only be applied in a fully explicit equation? I ask this because in the uploaded solvers, the 'fvm::laplacian()' operators have been changed to 'fvc::laplacian()'.
2. In a completely explict equation, there is no need to have separate predictor and corrector steps which is how this current solver is coded I believe, However, wouldn't this negatively affect accuracy?

On a separate note, I would like to know whether it is feasible to implement RK4 as a standalone ddtScheme like EulerDdtScheme because, so far, I don't think it is possible.

It would be extremely helpful if anyone could enlighten me on these issues.

Many thanks,
USV