[Nek5000-users] Computing total kinetic energy

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

Hi Praveen,

Yes - this is correct.

The "glsc3" stands for

     global scalar product, 3 arguments

and thus is fully parallel.

If you wanted (for some reason) a result local to each
processor, you would use

     vlsc3, which stands for vector local scalar product, 3 arguments.

An example would be:

        integer e
        real ek(lelt)

        nxyz = nx1*ny1*nz1
        do e=1,nelv
           ek(e) = (vlsc3(vx(1,1,1,e),vx(1,1,1,e),bm1(1,1,1,e),nxyz)
       $         +  vlsc3(vy(1,1,1,e),vy(1,1,1,e),bm1(1,1,1,e),nxyz)
       $         +  vlsc3(vz(1,1,1,e),vz(1,1,1,e),bm1(1,1,1,e),nxyz)) /2.
        enddo

Paul


On Tue, 4 Dec 2012, nek5000-users at lists.mcs.anl.gov wrote:

> Hello
>
> I use following code to compute total kinetic energy in the domain inside
> userchk
>
> c     Compute total kinetic energy
>      if(mod(istep,10).eq.0)then
>         n = nx1*ny1*nz1*nelv
>         xke = glsc3(vx, vx, bm1, n)
>         yke = glsc3(vy, vy, bm1, n)
>         zke = glsc3(vz, vz, bm1, n)
>         total_ke = 0.5*(xke + yke + zke)
>         if(nid.eq.0) write(6,1) istep, time, total_ke
>    1    format(i6,1p2e14.6,' Totalke')
>      endif
>
> Is this correct ? Does this account for the parallel computation or do I
> need to do something extra to gather from other processes ?
>
> Thanks
> praveen
>