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-   -   DG method, very small time step (https://www.cfd-online.com/Forums/main/116334-dg-method-very-small-time-step.html)

 Wenjun April 17, 2013 05:34

DG method, very small time step

When I apply the Discontinous Galerkin method on the KdV equation, the time step can only take very small number, like 0.0001. Can anyone tell me it is normal or not. Thanks !

 cfdnewbie April 17, 2013 05:38

Quote:
 Originally Posted by Wenjun (Post 421166) When I apply the Discontinous Galerkin method on the KdV equation, the time step can only take very small number, like 0.0001. Can anyone tell me it is normal or not. Thanks !

yeah, DG has a timestep of 1/(2n+1), where n is the ansatz degree. Which order is your ansatz?

 Wenjun April 17, 2013 05:43

Quote:
 Originally Posted by cfdnewbie (Post 421169) yeah, DG has a timestep of 1/(2n+1), where n is the ansatz degree. Which order is your ansatz?
I am a new guy of DG. I use the second-order element and the third-order TVD Runge-Kutta method. I set dx = 0.1, how should I choose the time step?

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