User roughness
Posted: Thu May 24, 2018 11:45 am
Dear all,
Could you tell the definition of user roughness parameter which is set up in the GUI. Is it "ks" value (Nikuradze roughness) or "y0" value. Or some other value?
In the source code (https://www.code-saturne.org/cms/sites/ ... ource.html) there is next lines about roughness:
That means user roughness is "ks" value which is ks=30*y0 roughly? Or maybe definition of roughness changes somewhere before?
Could you tell the definition of user roughness parameter which is set up in the GUI. Is it "ks" value (Nikuradze roughness) or "y0" value. Or some other value?
In the source code (https://www.code-saturne.org/cms/sites/ ... ource.html) there is next lines about roughness:
Code: Select all
688 /* Compute the friction velocity ustar */
689
690 /* Shifting of the wall distance to be consistant with
691 * the fully rough wall function
692 *
693 * ln((y+y0)/y0) = ln((y+y0)/alpha xi) + kappa * 5.2
694 *
695 * y0 = roughness * exp(-kappa * 8.5)
696 * */
697 double y0 = roughness*exp(-cs_turb_xkappa*cs_turb_cstlog_rough);