Numerical Calculation More Stable with Higher CFL number?

MrKnowHow · November 28, 2023, 18:59

Thus, I planned to use the Lax-Wendroff technique for numerical linear advection analysis. In terms of code, I believe my code works as planned. Nevertheless, it appears that my CFL=1 result is more stable than CFL = 0.5 when I run the code with different CFL values. Does it make sense? Or is there a mistake in my code?

FMDenaro · November 29, 2023, 04:36

Quote:

Originally Posted by MrKnowHow

Thus, I planned to use the Lax-Wendroff technique for numerical linear advection analysis. In terms of code, I believe my code works as planned. Nevertheless, it appears that my CFL=1 result is more stable than CFL = 0.5 when I run the code with different CFL values. Does it make sense? Or is there a mistake in my code?

No. The L-W is stable for c<=1. The specific case c=1 produces the exact solution but for c<1 the solution is always stable. What you see is the face that the solution is not monotone.
These are issues you should study in a CFD textbook.

November 28, 2023, 18:59	Numerical Calculation More Stable with Higher CFL number?	#1
MrKnowHow New Member Join Date: Feb 2022 Posts: 6 Rep Power: 4	Thus, I planned to use the Lax-Wendroff technique for numerical linear advection analysis. In terms of code, I believe my code works as planned. Nevertheless, it appears that my CFL=1 result is more stable than CFL = 0.5 when I run the code with different CFL values. Does it make sense? Or is there a mistake in my code?

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