Gmsh More Von Karman Vortex Street Movies


Contents


Introduction and Files
First tutorial (t2.geo)
Second and third tutorial (t3a.geo and t3b.geo)
Fourth tutorial (t4.geo)
Fifth tutorial (t5.geo)
Sixth tutorial (t6.geo)
Seventh tutorial (STL file of a man)
Eighth tutorial (Von Karman vortex street)

Appendix Eighth tutorial (Von Karman vortex street)

Laminar flow, Re 250

Velocity vectors.

Temperature. Cylinder wall heated, cold flow.

Vorticity. Result is postprocessed in VisIt using
"vorticity = 0.5*dot({0,0,1},curl(nvelocity))".

Detail of the velocity vectors immediately behind the cylinder.

Turbulent flow, Re 20,000

Higher Reynolds number, the viscosity lowered to 0.0001. Note the smaller wake and the less pronounced vortex street.

Start again with velocity vectors.

The velocity magnitude.

Temperature. Cylinder wall heated, cold flow.

Pressure. In the stagnation point it reads 0.5 Pa.

Vorticity. Result is postprocessed in VisIt using
"vorticity = 0.5*dot({0,0,1},curl(nvelocity))".

Turbulent kinetic energy k.

Turbulent dissipation rate epsilon.

Turbulent kinetic energy k and the turbulent dissipation rate epsilon combined result in the effective viscosity.

The turbulent kinetic energy k is a measure of the turbulent fluctuations and they can be related to the velocity magnitude giving the turbulent intensity i. Result is postprocessed in VisIt using
"intensity = sqrt(0.66666<k>) / (max(<velocity_magnitude>,0.001)) * 100.0".

From the turbulent kinetic energy k and the turbulent dissipation rate epsilon the turbulent length scale l can be derived. Result is postprocessed in VisIt using
"length_scale = 0.09^0.75 * <k>^1.5 / <eps>".


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