[Nektar-users] Noise Force Specification

8 Oct 2021

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Hi All,

What is the proper way to specify a noise force and a body force at the
same time?

I am new to Nektar++, and am attempting to run a simulation of turbulent
channel flow using a body force to drive the bulk flow, and a noise force
to generate some initial "turbulent-like" fluctuations of the velocity
field.  However, when I setup the case based on the details found in the
user guide (Forcing (nektar.info)
<https://doc.nektar.info/userguide/latest/user-guidese10.html#x16-810003.5> ),
the resulting flow field doesn't show any "noise component".  Is there some
error in my settings for this case?:

<NEKTAR>
   <CONDITIONS>
      ...
     <FUNCTION NAME="BodyForce">
             <E VAR="u" VALUE="-(Re*Kinvis/H)^2/H" />
             <E VAR="v" VALUE="0" />
             <E VAR="w" VALUE="0" />
         </FUNCTION>

     </CONDITIONS>
     <FORCING>
         <FORCE TYPE="Body">
             <BODYFORCE> BodyForce </BODYFORCE>
         </FORCE>
         <FORCE TYPE="Noise">
             <WHITENOISE> 0.5 </WHITENOISE>
             <UPDATEFREQ> 10 </UPDATEFREQ>
         </FORCE>
     </FORCING>
 </NEKTAR>

Regards,

*Marc Goldbach*
PhD Student, Department of Mechanical Engineering
University of North Carolina at Charlotte