Same Answer From 18% of the Cells — AMR Tagging Criteria and Coarse-Fine Refluxing
Wrapping a 256^2 shear layer in 3-level AMR leaves 11,776 cells, 18% of 65,536. Reflux off drifts mass by about 1% in 60 steps.
When Pressure Rings in a Checkerboard — SIMPLE and Rhie-Chow Coupling
On a 48-cell periodic line the naive stencil keeps a checkerboard of 0.80, while Rhie-Chow drives the same sawtooth down to 3.1e-16.
When Gradients Go Wrong on Skewed Meshes — Green–Gauss vs. Weighted Least-Squares Reconstruction
On a flat cell, Green–Gauss can swing the gradient nearly sideways. Distance-weighted least squares cuts the curved-field error from 0.0293 to 0.0222.
Solving an Impeller by Holding It Still — Rotating Frames and MRF
Coriolis and centrifugal sources at 1.2 rad/s, plus the MRF interface map from relative to absolute velocity, checked by a free particle.
[CFD Q&A] When simpleFoam Pressure Residual Fails to Converge
In simpleFoam the pressure residual jumped from 0.412 to 0.891. Dropping the p relaxation from 0.7 to 0.3 brought it near 1e-4 by iteration 200.
[OpenFOAM Tutorial] Backward Facing Step Flow Analysis — Capturing Recirculation Zones with simpleFoam
Scale 0.1 makes the step 0.1 m, while the viscosity note builds Re 1000 with H = 0.01 m. A 6–8H bubble then has two physical lengths.
Rhie-Chow Interpolation for Compressible Multiphase Flows
At a water-air density ratio of 1000, the arithmetic mean density is 500.5 and the harmonic mean is 2.0. Filter only the driving pressure.