<div dir="ltr"><div dir="ltr">On Mon, Apr 19, 2021 at 5:43 PM Sepideh Kavousi <<a href="mailto:skavou1@lsu.edu">skavou1@lsu.edu</a>> wrote:<br></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<span style="font-size:12pt;font-family:Calibri,Arial,Helvetica,sans-serif;font-weight:normal;text-indent:0px">Hello,</span><br>
<span style="font-size:12pt;font-family:Calibri,Arial,Helvetica,sans-serif;font-weight:normal;text-indent:0px">I want to solve PF solidification+Navier stokes using Finite different method. The Poisson equation is much more complicated that the one for just a
fluid-flow problems (because it includes different terms order parameter terms).</span></div>
<div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<span style="font-size:12pt;font-family:Calibri,Arial,Helvetica,sans-serif;font-weight:normal;text-indent:0px">The code converges but the convergence rate is very slow. I have tried different options. Following is the best options I found but the convergence
is still very slow. I did not include the ksp_convergence data because it takes around 1000 liner solver steps for each snes step.
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<span style="font-size:12pt;font-family:Calibri,Arial,Helvetica,sans-serif;font-weight:normal;text-indent:0px">I look in literature, but I did not find any data on PF+navierstokes solutions using Petsc. Do you have any suggestions how should I improve the convergence?</span></div></div></blockquote><div><br></div><div>First question: Are your nonlinear solves converging?</div><div><br></div><div> I see you have -snes_type ksponly, but it looks like your SNES iteration _diverges_ sometimes, and mostly fails to converge.</div><div> Is this correct?</div><div><br></div><div> Thanks,</div><div><br></div><div> Matt</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">
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<span style="font-size:12pt;font-family:Calibri,Arial,Helvetica,sans-serif;font-weight:normal;text-indent:0px">Best,</span></div>
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<span style="font-size:12pt;font-family:Calibri,Arial,Helvetica,sans-serif;font-weight:normal;text-indent:0px">Sepideh<br>
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<span style="font-size:12pt;font-family:Calibri,Arial,Helvetica,sans-serif;font-weight:normal;text-indent:0px"><span id="gmail-m_1424732035757749725🙂"></span></span><br>
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<div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
ibrun -np 136 ./one.out -ts_monitor -snes_fd_color -ts_max_snes_failures -1 -ts_type bdf -ts_bdf_adapt -snes_linesearch_type l2 -snes_type ksponly -pc_type fieldsplit -pc_fieldsplit_0_fields 0,1 -pc_fieldsplit_1_fields 2,3 -pc_fieldsplit_2_fields 4 -pc_fieldsplit_type
multiplicative -fieldsplit_0_pc_type bjacobi -fieldsplit_1_pc_type bjacobi -fieldsplit_2_pc_type ilu -fieldsplit_0_ksp_type preonly -fieldsplit_1_ksp_type preonly -fieldsplit_2_ksp_type preonly -sub_pc_type ilu -sub_ksp_type preonly -snes_monitor -log_view
log.txt<br>
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<div style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<div>TACC: Starting up job 7605521</div>
<div>TACC: Starting parallel tasks...</div>
<div>nu_nd=14948.511 !</div>
<div>tau/w=26225.459!</div>
<div>initial!</div>
<div>0 TS dt 0.0001 time 0.</div>
<div>copy!</div>
<div>Write output at step= 0!</div>
<div> 0 SNES Function norm 1.465357113711e+01</div>
<div> 1 SNES Function norm 1.131764004117e+02</div>
<div> 0 SNES Function norm 5.657793773935e+01</div>
<div> 1 SNES Function norm 9.539772669908e-02</div>
<div>1 TS dt 0.0002 time 0.0001</div>
<div>copy!</div>
<div> 0 SNES Function norm 1.734774194628e+02</div>
<div> 1 SNES Function norm 1.009134558763e+00</div>
<div>2 TS dt 0.000324128 time 0.0003</div>
<div>copy!</div>
<div> 0 SNES Function norm 1.199860231725e+01</div>
<div> 1 SNES Function norm 1.698885201785e-02</div>
<div>3 TS dt 0.000470679 time 0.000624128</div>
<div>copy!</div>
<div> 0 SNES Function norm 8.344934987594e+00</div>
<div> 1 SNES Function norm 4.082958856578e-03</div>
<div>4 TS dt 0.000769357 time 0.00109481</div>
<div>copy!</div>
<div> 0 SNES Function norm 9.338443428763e+00</div>
<div> 1 SNES Function norm 2.472903267511e-03</div>
<div>5 TS dt 0.00153871 time 0.00186416</div>
<div>copy!</div>
<div> 0 SNES Function norm 9.836384162921e+00</div>
<div> 1 SNES Function norm 6.383053421790e-03</div>
<div>6 TS dt 0.00215245 time 0.00340288</div>
<div>copy!</div>
<div> 0 SNES Function norm 5.043289760603e+00</div>
<div> 1 SNES Function norm 2.168332362305e-03</div>
<div>7 TS dt 0.0022353 time 0.00555533</div>
<div>copy!</div>
<div> 0 SNES Function norm 1.421255264272e+00</div>
<div> 1 SNES Function norm 1.750393691475e-03</div>
<div>8 TS dt 0.0044706 time 0.00779063</div>
<div>copy!</div>
<div> 0 SNES Function norm 1.216746389225e+00</div>
<div> 1 SNES Function norm 5.339123694240e-04</div>
<div> 0 SNES Function norm 2.168489818312e+00</div>
<div> 1 SNES Function norm 1.928809773415e-03</div>
<div>9 TS dt 0.00310217 time 0.0110885</div>
<div>copy!</div>
<div> 0 SNES Function norm 8.021629529051e-01</div>
<div> 1 SNES Function norm 2.161901383228e-04</div>
<div>10 TS dt 0.00300302 time 0.0141906</div>
<div>copy!</div>
<div> 0 SNES Function norm 7.731190774223e-01</div>
<div> 1 SNES Function norm 2.807020573793e-04</div>
<div>11 TS dt 0.00367968 time 0.0171937</div>
<div>copy!</div>
<div> 0 SNES Function norm 1.263830181443e+00</div>
<div> 1 SNES Function norm 1.049133009231e-02</div>
<div>12 TS dt 0.00704796 time 0.0208733</div>
<div>copy!</div>
<div> 0 SNES Function norm 5.619818748359e+00</div>
<div> 1 SNES Function norm 1.569218805659e-01</div>
<div>13 TS dt 0.00742462 time 0.0279213</div>
<div>copy!</div>
<div> 0 SNES Function norm 2.268051808662e+01</div>
<div> 1 SNES Function norm 7.055762930884e+00</div>
<div> 0 SNES Function norm 2.173806325395e+01</div>
<div> 1 SNES Function norm 1.564571270312e+00</div>
<div> 0 SNES Function norm 1.208038223084e+01</div>
<div> 1 SNES Function norm 5.192087605517e-02</div>
<div>14 TS dt 0.00186927 time 0.0299244</div>
<div>copy!</div>
<div> 0 SNES Function norm 4.797722218343e+00</div>
<div> 1 SNES Function norm 3.975928994156e-03</div>
<div>15 TS dt 0.00189622 time 0.0317937</div>
<div>copy!</div>
<div> 0 SNES Function norm 5.510229536082e+00</div>
<div> 1 SNES Function norm 4.496811351139e-03</div>
<div>16 TS dt 0.00172953 time 0.0336899</div>
<div>copy!</div>
<div> 0 SNES Function norm 6.945417639798e+00</div>
<div> 1 SNES Function norm 4.569326335543e-03</div>
<div>17 TS dt 0.00218527 time 0.0354194</div>
<div>copy!</div>
<div> 0 SNES Function norm 1.351474156680e+01</div>
<div> 1 SNES Function norm 1.719775600164e-02</div>
<div>18 TS dt 0.00224386 time 0.0376047</div>
<div>copy!</div>
<div> 0 SNES Function norm 2.174969556700e+01</div>
<div> 1 SNES Function norm 3.814212178889e-02</div>
<div> 0 SNES Function norm 4.891415655138e+01</div>
<div> 1 SNES Function norm 6.772042718901e-02</div>
<div> 0 SNES Function norm 2.828143585009e+01</div>
<div> 1 SNES Function norm 6.965842377755e-03</div>
<div> 0 SNES Function norm 2.168193335917e+01</div>
<div> 1 SNES Function norm 2.463212234975e-03</div>
<div>19 TS dt 0.000205482 time 0.0378175</div>
<div>copy!</div>
<div> 0 SNES Function norm 1.409435206457e+00</div>
<div> 1 SNES Function norm 1.859628755245e-02</div>
<div>20 TS dt 0.000188785 time 0.0380229</div>
<div>copy!</div>
<div>Write output at step= 20!</div>
<div> 0 SNES Function norm 5.900261363044e-01</div>
<div> 1 SNES Function norm 2.653576084845e-02</div>
<div> 0 SNES Function norm 5.122905363140e+00</div>
<div> 1 SNES Function norm 4.297068425492e-03</div>
<div> 0 SNES Function norm 3.428448792746e+00</div>
<div> 1 SNES Function norm 1.000610664096e-02</div>
<div>21 TS dt 6.50511e-05 time 0.0380738</div>
<div>copy!</div>
<div> 0 SNES Function norm 3.700405789863e-01</div>
<div> 1 SNES Function norm 6.263642369355e-02</div>
<div>22 TS dt 7.93452e-05 time 0.0381388</div>
<div>copy!</div>
<div> 0 SNES Function norm 5.282939288286e-01</div>
<div> 1 SNES Function norm 3.003209840754e-01</div>
<div>23 TS dt 7.50242e-05 time 0.0382181</div>
<div>copy!</div>
<div> 0 SNES Function norm 7.079201595974e-01</div>
<div> 1 SNES Function norm 1.247544399226e-02</div>
<div>24 TS dt 0.000150048 time 0.0382932</div>
<div>copy!</div>
<div> 0 SNES Function norm 6.197633272307e-01</div>
<div> 1 SNES Function norm 3.176914154297e-02</div>
<div>25 TS dt 0.000171939 time 0.0384432</div>
<div>copy!</div>
<div> 0 SNES Function norm 5.849423362557e-01</div>
<div> 1 SNES Function norm 9.462256964187e-03</div>
<div>26 TS dt 0.000176855 time 0.0386152</div>
<div>copy!</div>
<div> 0 SNES Function norm 4.304951653234e-01</div>
<div> 1 SNES Function norm 3.939112950208e-03</div>
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div>What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>-- Norbert Wiener</div><div><br></div><div><a href="http://www.cse.buffalo.edu/~knepley/" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><br></div></div></div></div></div></div></div></div>