[Nek5000-users] Variable density flows

Sat Oct 12 12:28:16 CDT 2013

Hi
My problem is flow in a 2d channel. The initial condition is zero velocity
in the channel and there is an inlet flow. I have a passive scalar which is
flowing in through inlet. Initial temperature is zero everywhere. I am
having trouble getting initial iterations to converge. I am trying stress
formulation and passive scalars for first time and I do not see what is
going wrong.

             Solving for heat
 Solving for fluid F F T
  Temperature/Passive scalar solution
   1.0000000000000001E-009  p22            1           2
 New CG1-tolerance (RINIT*epsm) =    8.4585499354425527E-033   2.
    5514287912844953E-033
  1     1 Helmholtz TEMP    F:   8.4585E-20   1.0000E-09   2.8571E-04
0.0000E+00
          1    Hmholtz TEMP:      0   8.4585E-20   8.4585E-20   1.0000E-09
   1.0000000000000001E-009  p22            1           2
 New CG1-tolerance (RINIT*epsm) =    5.8174583141330990E-032   1.
    7860001538991468E-032
  1     1 Helmholtz PS 1    F:   5.8175E-19   1.0000E-09   2.0000E-03
0.0000E+00
          1    Hmholtz PS 1:      0   5.8175E-19   5.8175E-19   1.0000E-09
          1   0.0000E+00  6.0799E-03 Heat done
 New CG1(stress)-tolerance (RINIT*epsm) =    6.9206392325228944E-014   4.
    2096427334076814E-033
  0  1.0000E-09  6.9206E-14  1.0000E-09 tol,matmod
           1 tx3:      1   0.3584E+00   0.1000E-08   0.3584E+00
           1 tx3:      2   0.2546E+00   0.1000E-08   0.3584E+00
           1 tx3:      3   0.1905E+00   0.1000E-08   0.3584E+00
.
.
.
           1 tx3:    198   0.1080E-02   0.1000E-08   0.3584E+00
           1 tx3:    199   0.1067E-02   0.1000E-08   0.3584E+00
           1 tx3:    200   0.1033E-02   0.1000E-08   0.3584E+00
     1   201 Unconverged Helmholtz3/Fluid: rbnorm = 0.103306E-02
0.100000E-08
    1 1.00000E-07 2.34297E-01 2.34297E-01 1.00000E+00       1 Divergence
 New CG1(stress)-tolerance (RINIT*epsm) =    1.5438583947746548E-016   4.
    2096427334076814E-033
  0  1.0000E-09  1.5439E-16  1.0000E-09 tol,matmod
           1 tx3:      1   0.8855E-02   0.1000E-08   0.8855E-02
           1 tx3:      2   0.5463E-02   0.1000E-08   0.8855E-02
           1 tx3:      3   0.5217E-02   0.1000E-08   0.8855E-02

Thanks a lot
praveen

On Sat, Oct 12, 2013 at 10:04 PM, <nek5000-users at lists.mcs.anl.gov> wrote:

>
> Hi Praveen,
>
> That looks right... As always, it's best to run a test
> to verify first.
>
> Paul
>
>
> ----- Original Message -----
> From: nek5000-users at lists.mcs.anl.gov
> To: nek5000-users at lists.mcs.anl.gov
> Sent: Saturday, October 12, 2013 11:17:06 AM
> Subject: Re: [Nek5000-users] Variable density flows
>
>
>
> Thanks to Paul and Ammar. I will try the variable density approach.
>
>
> I am first trying a case in which viscosity depends on temperature and a
> passive scalar. My uservp looks like this. Can I use "temp" and "PS" to get
> temperature and passive scalar as below ?
>
>
>
> subroutine uservp (ix,iy,iz,ieg)
> include 'SIZE'
> include 'TOTAL'
> include 'NEKUSE'
> common /mygeom/ xmin,xmax
> common /myparam/ r_k,Rey_no,Pr_no,Sc_no,visc_rat
>
>
> if(ifield.eq.1)then ! momentum equation
> utrans= 1.0
> udiff = exp(PS(1)*log(visc_rat) - temp)/Rey_no
> else if(ifield.eq.2)then ! temperature eqn
> utrans= 1.0
> udiff = PS(1)*(r_k - 1.0) + 1.0
> udiff = udiff/(Rey_no*Pr_no)
> else if(ifield.eq.3)then ! passive scalar
> utrans= 1.0
> udiff = 1.0/(Rey_no*Sc_no)
> else
> print*,'Only 3 fields'
> call exitt()
> endif
>
>
> return
> end
>
>
> Thanks
> praveen
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