VOF: wall shear stresses over time

idrama · September 25, 2010, 03:46

Hallo folks,

I have the following problem. I ran a VOF simulation and would like to know how can I visualized the wall shear stresses over time?

Thanks in advanced

valgrinda · September 27, 2010, 09:22

Hei,

in case the turbulent kinetic energy k is available in your result files, you can multiply k at the wall with $\sqrt{c_{\mu}}\rho$ , then you get the shear stress $\tau$ . An other alternative is to use the velocities: $\tau = \rho u_*^2 = \rho \frac{u \left| u \right|}{ \left(u^+\right)^2 }$ with u+ coming from Schlichting's smooth or rough wall laws. In your case, $\rho$ depends on the VOF volume fraction function.

Cheers
Hans

idrama · October 12, 2010, 11:46

Thank you for you answer! But can I actually just take the integral of tau(x,t) over time? tau(x,t) wall shear stress at time t at position x.

September 25, 2010, 03:46	VOF: wall shear stresses over time	#1
idrama Senior Member Claus Meister Join Date: Aug 2009 Location: Wiesbaden, Germany Posts: 241 Rep Power: 18	Hallo folks, I have the following problem. I ran a VOF simulation and would like to know how can I visualized the wall shear stresses over time? Thanks in advanced

September 27, 2010, 09:22	Wall Shear Stress	#2
valgrinda Super Moderator Hans Bihs Join Date: Jun 2009 Location: Trondheim, Norway Posts: 403 Rep Power: 19	Hei, in case the turbulent kinetic energy k is available in your result files, you can multiply k at the wall with $\sqrt{c_{\mu}}\rho$ , then you get the shear stress $\tau$ . An other alternative is to use the velocities: $\tau = \rho u_*^2 = \rho \frac{u \left\| u \right\|}{ \left(u^+\right)^2 }$ with u+ coming from Schlichting's smooth or rough wall laws. In your case, $\rho$ depends on the VOF volume fraction function. Cheers Hans

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October 12, 2010, 11:46		#3
idrama Senior Member Claus Meister Join Date: Aug 2009 Location: Wiesbaden, Germany Posts: 241 Rep Power: 18	Thank you for you answer! But can I actually just take the integral of tau(x,t) over time? tau(x,t) wall shear stress at time t at position x.