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Turbulence kinetic energy and dissipation rate - problem with computation |
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March 6, 2015, 05:04 |
Turbulence kinetic energy and dissipation rate - problem with computation
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jiri kozak
Join Date: Jan 2013
Posts: 21
Rep Power: 13 |
Hello!
I'm quite new in OpenFoam and Python, therefore I have decided to write short script for the turbulence kinetic energy and dissipation rate computation.Code of the sripts follows: def VypocetTurbVelicin(velocity, hydraulic_diameter, mu): reynolds = (velocity * hydraulic_diameter)/mu cmu = 0.09 intensity = 0.05 fluct_velocity = intensity * velocity global k k = 3/2 * ((fluct_velocity)**2) turbulence_lengthScale = 0.038 * hydraulic_diameter global epsilon epsilon = (cmu * k**(3/2))/turbulence_lengthScale return k, epsilon k = None velocity = float(raw_input("Velocity: ")) hydraulic_diameter = float(raw_input("Hydraulic diamter: ")) mu = float(raw_input("Kinematic viscosity : ")) VypocetTurbVelicin(velocity, hydraulic_diameter, mu) print "turbulence kinetic energy: " + str(k) print "turbulence dissipation rate: " + str(epsilon) Problem is that the results of my script are different compared to the calculator which is available on the cfd-online (http://www.cfd-online.com/Tools/turbulence.php) I can't find the problem. Thank you very much for any advice For example results for vel = 4.2 m.s^(-1) visc = 1E-6 m^(2).s^(-1) hydraulic diameter = 0.3 m turbulence intensity = 5% are: My script: k = 0.0441 eps = 0.348157894737 CFD online calculator (Turbulence variables (k, ε, ω) from turbulence intensity (Tu), length-scale (TuL) and freestream velocity (U∞)): k = 0.06615000000000001 eps = 0.13431744774423365 |
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dissipation rate, epsilon, kinetic energy, openfoam, turbulence |
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