Reply To: Using example (cylinder3D)

[H.Yu]

thanks for your comment

I am trying to perform turbulence on an airfoil using the 3D cylinder example.
What is the difference between physics speed and lattice speed, kinematic viscosity?

If i set the Reynolds number to 50000 and proceed, the output will be as follows.
Can you help? I am attaching both Input and Output. thank you.

This is the source code ‘unitconverter.h’.
/// return Reynolds number
constexpr T getReynoldsNumber( ) const
{
return _charPhysVelocity * _charPhysLength / _physViscosity;
}

INPUT : (Reynolds Number = 50000 )
UnitConverter<T, DESCRIPTOR> converter(
(T) 0.1/N, // physDeltaX: spacing between two lattice cells in __m__
(T) 0.1/(M*N), // physDeltaT: time step in __s__
(T) 0.1, // charPhysLength: reference length of simulation geometry
(T) 7.504, // charPhysVelocity: maximal/highest expected velocity during simulation in __m / s__
(T) 1.2*7.504*0.1/Re, // physViscosity: physical kinematic viscosity in __m^2 / s__
(T) 1.2 // physDensity: physical density in __kg / m^3__
);
// Prints the converter log as console output
converter.print();

OUTPUT :
[UnitConverter] —————– UnitConverter information —————–
[UnitConverter] — Parameters:
[UnitConverter] Resolution: N= 40
[UnitConverter] Lattice velocity: latticeU= 0.3752
[UnitConverter] Lattice relaxation frequency: omega= 0.312359
[UnitConverter] Lattice relaxation time: tau= 3.20144
[UnitConverter] Characteristical length(m): charL= 0.1
[UnitConverter] Characteristical speed(m/s): charU= 7.504
[UnitConverter] Phys. kinematic viscosity(m^2/s): charNu= 0.045024
[UnitConverter] Phys. density(kg/m^d): charRho= 1.2
[UnitConverter] Characteristical pressure(N/m^2): charPressure= 0
[UnitConverter] Mach number: machNumber= 0.649865
[UnitConverter] Reynolds number: reynoldsNumber= 16.6667
[UnitConverter] Knudsen number: knudsenNumber= 0.0389919
[UnitConverter]
[UnitConverter] — Conversion factors:
[UnitConverter] Voxel length(m): physDeltaX= 0.0025
[UnitConverter] Time step(s): physDeltaT= 0.000125
[UnitConverter] Velocity factor(m/s): physVelocity= 20
[UnitConverter] Density factor(kg/m^3): physDensity= 1.2
[UnitConverter] Mass factor(kg): physMass= 1.875e-08
[UnitConverter] Viscosity factor(m^2/s): physViscosity= 0.05
[UnitConverter] Force factor(N): physForce= 0.003
[UnitConverter] Pressure factor(N/m^2): physPressure= 480
[UnitConverter] ————————————————————-