CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   OpenFOAM (http://www.cfd-online.com/Forums/openfoam/)
-   -   Numerical schemes for grad and div (http://www.cfd-online.com/Forums/openfoam/108104-numerical-schemes-grad-div.html)

Tobi October 15, 2012 05:29

Numerical schemes for grad and div
 
Hello Foamers,

I have a question to some schemes in OpenFOAM.


grad-Scheme
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

What is the differences between
Code:

grad(U)        Gauss linear;
grad(U)        cellLimited Gauss linear 1;

Its clear that I use a limiter for the grad schemes. But does that mean, that the change of U^{n-1} to U^n is limited? Is my interpretation correct?

div-Scheme
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Whats the difference between

Code:

div(phi, Z)          Gauss limitedLinear 1 0 1
div(phi, Z)          Gauss limitedLimitedLinear 1 0 1

I think the first scalar is for the limiter. 1=full limiter 0=non limiter. The values after that are bouding parameters? so that the variable Z is bounded between [0-1] ? is that correct? And the differences between both?


Any suggestion would be very nice.
Regard
Tobi

immortality February 27, 2013 11:38

hi
can anyone answer to these questions?
thanks.

Tobi March 11, 2013 17:10

Hi all,

results of different schemes can be found on my homepage (its unfortunatelly german but with graphics)

http://www.holzmann-cfd.de/index.php...rische-schemen

ngj March 11, 2013 17:31

Hi Tobias,

Nice graphics:) Just a quick question from a non-German speaking person. Is it a pure advection problem, which you have been solving?

At least with a quick view on a couple of the cases, it seems that you are only changing the divergence scheme.

Thanks,

Niels

akidess March 11, 2013 17:41

Niels, indeed the site states pure convection ("reine Konvektion").

Tobi March 11, 2013 17:45

Hi,

yes I am only changing the div schemes to get influence of konvection influence ... "there is no diffusivity". That s necessary to get see what influence the different schemes are make in the equations.

dkokron March 11, 2013 22:24

I found the following paper that includes some other results along the same lines as Tobi. The paper includes the step function and two other shapes.

http://powerlab.fsb.hr/ped/kturbo/Op...GammaPaper.pdf

Dan


All times are GMT -4. The time now is 17:01.