Friction coefficient
 

Help needed...

I am new to Flow3D, I'm trying to model the shock tube using the standard example model as a base. But it is impossible to change friction coefficient in turbulence settings (it is always -1.0). I've tried to change fluid viscousity and other parameters but that doesn't solve the problem. Friction is still -1.0.

Thanks in advance!

You need to activate the viscous model in Physics > Viscosity and Turbulence. Make sure also that there is a non-zero viscosity coefficient in the fluid properties.

Using a positive friction coefficient means a partial slip at walls. Is it what you want to do for the gas?

Yes, I've tried what you said. Nothing helps. Miha! Pls. check your private inbox. Thx

Gleb,

If you have viscous flow activated and the viscosity is positive, then there is friction at walls. The friction coefficient stays at -1, as it should for all fluid. The -1 value effectively means infinite no-slip BC. A 0 value would mean free slip, and a positive value means partial slip, which is suitable for solid-like materials.

The fact that you do not see a noticeable effect on the shock is probably because the viscous boudnary layer is too thin to be resolved.

dear Belgio,i have the same problem ,have you ever solved the problem?i want to set the frictional coefficient zero.thanks.

No, I have not solved that.

Hi guys,

Do I understand correctly that you have not been able to simulate a shock wave in a test tube because you could not set a friction coefficeint?