# Y plus Calculation

 Register Blogs Members List Search Today's Posts Mark Forums Read

 January 31, 2017, 08:03 Y plus Calculation #1 New Member   Alejo Join Date: Mar 2014 Posts: 1 Rep Power: 0 Hello everyone, I would like to know how Fluent calculates de Y+ parameter from the velocity field ? I know the definition of this parameter: Y+ = U_tau * Y_node / Kinematic_Viscosity With Y_node the distance from the center of the volumen to the wall; ans U_tau the friction velocity. This velocity is calculated as: U_tau = (T_tau / Fluid density)^(1/2) With T_Tau the wall shear stress. This value is deficed as: T_Tau = Dynamic_Viscosity * (du/dy)_(y=0) With (du/dy)_(y=0) the slope of the parallel velocity in the normal direction to the wall. What I do not understand is how I could determine this derivate value at the wall if I only have the velocity field at the center of the control volume closet to the wall? Besides, when I am using a wall function I am far from the wall, so how can I obtain the value of the friction velocity? Does Fluent use the log-velocity profile to define if the cell is in the sub-viscous layer or the turbulent layer ? Best, Alejandro

 Tags friction velocity, log. velocity-profile, wall shear stress, yplus

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are Off Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post xh110120 FLUENT 1 March 12, 2016 08:05 peterhess OpenFOAM Running, Solving & CFD 4 March 9, 2016 03:07 Davitt COMSOL 0 January 14, 2016 14:16 Susan YU FLUENT 0 June 2, 2010 08:46 AB Siemens 6 November 15, 2004 04:41

All times are GMT -4. The time now is 00:58.