[Nek5000-users] ffx ffy ffz in usr

[nek5000-users at lists.mcs.anl.gov]

I guess u_t is the friction velocity u_tau and u_b the bulk velocity
(for a channel). So that just means that the forcing ffx in the 
streamwise direction will lead to a specific friction Reynolds number 
(fixed pressure gradient) in channel flow. In other cases, where there 
is no external pressure gradient (like boundary layers), you do not need 
to use ffx to drive the flow.

Philipp

On 2018-01-23 18:23, nek5000-users at lists.mcs.anl.gov wrote:
> Thai,
> 
> if you are referring to ffx, ffy and ffz from the usr file they are
> accelerations applied to the x, y and z momentum equations,
> respectively.
> 
> What is the meaning of u_t and u_b?
> 
> Marco
> 
> 
>> On Jan 23, 2018, at 12:14 PM, nek5000-users at lists.mcs.anl.gov
>> wrote:
>> 
>> Hi Nek,
>> 
>> Is there anyone know whether the ffx ffy and ffz are pressure
>> gradient? And why it is set to be (u_t/u_b)^2 and sometimes set to
>> be 0? What's difference between those curcumstance and what else we
>> can do to let them to be equal?
>> 
>> Kind regards,
>> 
>> Zhai _______________________________________________ Nek5000-users
>> mailing list Nek5000-users at lists.mcs.anl.gov 
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