CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   Main CFD Forum (http://www.cfd-online.com/Forums/main/)
-   -   convergence of DG for Euler equations (http://www.cfd-online.com/Forums/main/16284-convergence-dg-euler-equations.html)

Shyam February 1, 2009 22:01

convergence of DG for Euler equations
 
Hi,

I am developing a CFD code for unstructured grids based on spectral and DG methods. I used linear advection and Burger's eqn to get the order of convergence of the code. The scheme performed pretty good. But, when I use the same for Euler code, I am not able to get the designed order of error convergence. I used the advection of isentropic vortex for testing the Euler code. For the flux, I used HLL fluxes. Can anyone let me know what fluxes are recommended for the DG schemes of order > 3?

Also, in the HLL flux, the normal flux is something like

F_HLL = (SR*FL - SL*FR + SL*SR*(qR-qL))/(SR-SL)

I have used the fluxes FL and FR as the normal fluxes and qL and qR to be the original state variables (not transformed to normal coordinates). If I am wrong in this, please correct me.

Thanks, Shyam


Shyam February 2, 2009 04:19

Re: convergence of DG for Euler equations
 
Hi All,

I figured out that the code produces the desired order of accuracy if a more benign problem is chosen. When I chose the initial condition to be rho = 1 + 0.2 * sin(PI*(x+y)), u=0.7, v=0.2, p=1

the code produced the expected results. Still wondering why it struggles for advection of isentropic vortex.

Shyam

jack February 7, 2009 01:48

Re: convergence of DG for Euler equations
 
i am a DG worker too MSN: dirac_euler@hotmail.com


All times are GMT -4. The time now is 23:10.