用rhoPimpleFoam计算飞机外流，为什么iteration为0

好好科研

各位大佬，想问一下我计算一个飞机模型的外流，设置的dt为2e-8，但是不知道为什么从最开始就是No Iterations 0，这是没在计算嘛？刚开始设置的dt为5e-8，计算一段时间就发散了。

Courant Number mean: 7.5311001e-06 max: 0.56432736
Time = 1.2e-07

diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCGStab:  Solving for Ux, Initial residual = 6.9178663e-11, Final residual = 6.9178663e-11, No Iterations 0
DILUPBiCGStab:  Solving for Uy, Initial residual = 2.5448919e-10, Final residual = 2.5448919e-10, No Iterations 0
DILUPBiCGStab:  Solving for Uz, Initial residual = 4.2785621e-10, Final residual = 4.2785621e-10, No Iterations 0
DILUPBiCGStab:  Solving for e, Initial residual = 9.7719937e-09, Final residual = 1.0109782e-12, No Iterations 1
GAMG:  Solving for p, Initial residual = 7.8947472e-09, Final residual = 7.8947472e-09, No Iterations 0
GAMG:  Solving for p, Initial residual = 7.8947472e-09, Final residual = 7.8947472e-09, No Iterations 0
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 1.0995375e-11, global = -1.6176582e-13, cumulative = -8.4645739e-13
GAMG:  Solving for p, Initial residual = 7.8947534e-09, Final residual = 7.8947534e-09, No Iterations 0
GAMG:  Solving for p, Initial residual = 7.8947534e-09, Final residual = 7.8947534e-09, No Iterations 0
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 1.0995384e-11, global = -1.6176582e-13, cumulative = -1.0082232e-12
DILUPBiCGStab:  Solving for nuTilda, Initial residual = 9.7105217e-10, Final residual = 9.7105217e-10, No Iterations 0

Number44

@好好科研 iteration为0是因为Initial residual达到了收敛要求了，就是tolerance到了你设的值了。
从Courant Number判断，现在的时间步长应该是合适的。不过rho没有迭代，没用过这个，不清楚是否正常。

xpqiu

要么调小 U 的 tolerance，要么强制设置 minIter 为1，也就是在 U 里面设置

minIter   1;

这样保证至少求解一次。

好好科研

@number44 我这个p和U的tolerance分别设置的是1e-8和1e-9，感觉挺小的，还要调的更小嘛

Number44

@好好科研在用rhoPimpleFoam计算飞机外流，为什么iteration为0 中说：

@number44 我这个p和U的tolerance分别设置的是1e-8和1e-9，感觉挺小的，还要调的更小嘛

通常来讲，够有多了，我一般就是1E-6到1E-8而已。