rhoCentralFoam_RK4_LTS

• Little modification of rhoCentralFoam with RK4 schme, also LTS exits.
• Ref: dbns-port, cfd-online, rhoCentralRK4Foam, using CFL to speed up:relax，TODO:add sponge layer
• Acknowledge：Du Lei

Validation:

01:shockTube

• 1 parameter: rhoCentralFoam,LTS,maxCo=0.2(not correct);rhoCentralFoamRK4,LTS,maxCo=0.2;

• 2 parameter: rhoCentralFoam,LTS,maxCo=0.01(correct);rhoCentralFoamRK4,LTS,maxCo=0.2;

which means rhoCentralFoamRK4 is more effecient in same setting!

02:sineWave

02:inf which is better? smaller

etA should balance between "drift" and "wall" , etA==1 is suggested.

CFL Selection

• Large Eddy Simulation $(0.5-1)$
• Free Surface Flows $(<1)$
• Compressible Flows (depends on speed of sound)
• Turbomachinery $(<80)$
• Explicit Time Stepping $(<1)$.

Most often the maximum Courant number should be below 1.0.

• Suggestion: set CFL=0.3~0.5 at first, the enlarge it to CFL=0.5~1.7 , 1.8 is broken up

Quesion:

• use "bounded" or "unbounded" : most "bounded" is for steady flow, 为了使求解稳定