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<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;">Dear all,<br>
<br>
I am new to Nek5000 and am trying to output the velocity divergence of my 2D, unsteady N-S solution for a flat plate with elliptic leading edge using PN-PN-2 formulation.
<br>
<br>
I compute divergence using gradm1() and opdiv() and the values I get from the two don't seem to match the DIVERGENCE and HELMHOLTZ (p021 and p022) residuals in the .rea file (which are 1e-9 and 1e-11). I get div ~ 1 using gradm1() and div~1e-2 using opdiv()
and the divergence is close to the elliptic leading edge. Am I missing something(scaling factor maybe?) in the computation of divergence here?<br>
<br>
subroutine userchk<br>
include 'SIZE'<br>
include 'TOTAL'<br>
<br>
common /scren/ vort (lx1,ly1,lz1,lelv,3) ! x y z components<br>
$ , work1(lx1,ly1,lz1,lelv)<br>
$ , work2(lx1,ly1,lz1,lelv)<br>
$ , dudx(lx1,ly1,lz1,lelv)<br>
$ , dvdy(lx1,ly1,lz1,lelv)<br>
$ , div1(lx1,ly1,lz1,lelv)<br>
$ , div2(lx2,ly2,lz2,lelv)<br>
$ , div3(lx1,ly1,lz1,lelv)<br>
<br>
n = nx1*ny1*nz1*nelt<br>
ntot2 = nx2*ny2*nz2*nelt<br>
<br>
c Compute divergence using gradm1()<br>
call gradm1(dudx,work1,work2,vx)<br>
call gradm1(work1,dvdy,work2,vy)<br>
div1 = dudx + dvdy<br>
<br>
<br>
c Compute divergence using opdiv()<br>
call opdiv(div2,vx,vy,vz)<br>
c opdiv returns bm2*div<br>
call col2(div2,bm2inv,ntot2)<br>
<br>
call mappr(div3,div2,work1,work2)<br>
if(nid .eq.0)write(6,*)'Done mapping div2 to xm1'<br>
<br>
call outpost(div1,div3,vx,pr,vort(:,:,:,:,1),<br>
& 'divvort')<br>
<br>
return<br>
end<br>
<br>
This is from the output file showing the DNORM, DIVEX<br>
<br>
Step 2, t= 4.0340639E+00, DT= 1.0892282E-04, C= 0.500 2.1168E+01 2.1168E+01<br>
Solving for fluid F T T<br>
9.999999999999999E-012 p22 2 1<br>
2 Hmholtz VELX: 42 6.4400E-12 8.2479E-02 1.0000E-11<br>
9.999999999999999E-012 p22 2 1<br>
2 Hmholtz VELY: 40 6.3878E-12 9.2957E-02 1.0000E-11<br>
2 U-PRES gmres: 120 6.0275E-08 1.0000E-09 6.4717E-04 5.7658E+00 1.6938E+01<br>
2 DNORM, DIVEX 6.027476742433520E-008 6.027476742402435E-008<br>
2 4.0341E+00 2.0912E+01 Fluid done<br>
<br>
Thanks<br>
Prahladh Iyer<br>
Postdoctoral Researcher<br>
National Institute of Aerospace, Hampton, Virginia<br>
Resident: NASA Langley Research Center<br>
Email : prahladh.s.iyer@nasa.gov<br>
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