openfoam-51-y-verification

name	openfoam-51-y-verification
description	Sub-skill of openfoam: 5.1 y+ Verification (+5).
version	1.0.0
category	engineering
type	reference
scripts_exempt	true

5.1 y+ Verification (+5)

5.1 y+ Verification

# Compute y+ post-hoc
simpleFoam -postProcess -func yPlus -latestTime

Or add to controlDict:

functions { #includeFunc yPlus }

Target y+ ranges:

Approach	y+ target	When to use
Wall-resolved (low-Re)	< 1	Accurate wall heat transfer, separation
Wall functions (high-Re)	30-300	Industrial flows, coarser meshes
Buffer layer (avoid)	5-30	Neither model accurate here

5.2 Mass Conservation

Parse continuity errors from log:

time step continuity errors : sum local = 1.23e-07, global = -2.34e-15, cumulative = -5.67e-14

Metric	Acceptable
sum local	< 1e-4 (typical: 1e-6 to 1e-8)
global	< 1e-10 (should be near machine precision)
cumulative	Should not grow unbounded

5.3 Residual Convergence Criteria

Steady-state (simpleFoam):

Field	Typical target	Tight target
p	initial residual < 1e-4	< 1e-5
U	initial residual < 1e-4	< 1e-5
k, epsilon, omega	initial residual < 1e-4	< 1e-5

Convergence: residuals should decrease monotonically. Oscillating residuals indicate numerical issues.

Transient: Final residuals within each time step should reach solver tolerance. Initial residuals should not grow over successive time steps.

5.4 Benchmark Cases

Available locally at /usr/lib/openfoam/openfoam2312/tutorials/:

Lid-Driven Cavity (icoFoam):

# Path: tutorials/incompressible/icoFoam/cavity/cavity/
blockMesh && icoFoam
# Validates: PISO, basic BCs
# Expected: single primary vortex at Re=100, compare with Ghia et al. (1982)

Backward-Facing Step — pitzDaily (simpleFoam):

# Path: tutorials/incompressible/simpleFoam/pitzDaily/
blockMesh && simpleFoam
# Validates: SIMPLE, k-epsilon turbulence, wall functions
# Expected: reattachment at ~6-7 step heights downstream

Dam Break (interFoam):

# Path: tutorials/multiphase/interFoam/laminar/damBreak/damBreak/
blockMesh && setFields && interFoam
# Validates: VOF, free surface, interFoam

motorBike (simpleFoam + snappyHexMesh):

# Path: tutorials/incompressible/simpleFoam/motorBike/
# Full parallel workflow with snappyHexMesh
# Validates: complex geometry meshing, parallel execution, force coefficients

5.5 Function Objects for Monitoring

Include in controlDict functions {}:

Name	Purpose
#includeFunc yPlus	Wall y+ field
#includeFunc CourantNo	Courant number field
#includeFunc fieldMinMax	Min/max of all fields
#includeFunc solverInfo	Residual data per timestep
#includeFunc wallShearStress	Wall shear stress
#includeFunc vorticity	Vorticity field
#includeFunc Q	Q criterion for vortex identification

All function object templates at: /usr/lib/openfoam/openfoam2312/etc/caseDicts/postProcessing/

5.6 Export for ParaView

foamToVTK                                # all times -> VTK/ directory
foamToVTK -latestTime                    # latest only
foamToVTK -fields '(U p)'               # specific fields
foamToVTK -time '100:200'               # time range

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