<div dir="ltr">Hello<div>I am solving a 2d flow with variable viscosity using stress formulation. The viscosity depends on a scalar concentration which is advected/diffused and the viscosity varies by an order of magnitude in the domain. The helmholtz iterations seems to converge slowly as shown here</div>
<div><br></div><div><p style="margin:0px;font-size:11px;font-family:Menlo">Step 39998, t= 3.9998000E+01, DT= 1.0000000E-03, C= 0.346 7.2489E+03 1.1492E-01 </p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> Solving for heat </p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> Solving for fluid F T T</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 39998 Hmholtz TEMP: 7 2.9893E-10 3.3026E+00 1.0000E-09</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 39998 Hmholtz<span style="background-color:rgb(230,230,0)"> PS </span>1: 4 6.7160E-11 2.1011E+00 1.0000E-09</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 39998 3.9998E+01 6.9721E-03 Heat done</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 39998 Helmholtz3/fluid: 35 0.9267E-09 0.1000E-08 0.1398E+00</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 39998 U-PRES gmres: 7 9.4465E-08 1.0000E-07 4.4910E-05 6.1851E-03 1.3509E-02</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 39998 DNORM, DIVEX 9.44654494640397541E-008 9.44654494679585123E-008</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 39998 3.9998E+01 4.3178E-02 Fluid done</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 39998 3 qfilt: 3.6770E-08 7.2251E-10</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 4.6167E-10 3.8497E-09</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> Compute statistics ...</p><p style="margin:0px;font-size:11px;font-family:Menlo"><br></p>Is there any way to improve the convergence. My parameters are given below.</div>
<div><br></div><div>Thanks</div><div>praveen</div><div><br></div><div><p style="margin:0px;font-size:11px;font-family:Menlo">****** PARAMETERS *****</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 2.6099999 NEKTON VERSION</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 2 DIMENSIONAL RUN</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 118 PARAMETERS FOLLOW</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 1.00000 p001 DENSITY</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 1.00000 p002 VISCOS</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p003</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p004</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p005</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p006</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 1.00000 p007 RHOCP</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.100000E-01 p008 CONDUCT</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p009</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 40.00000 p010 FINTIME</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p011 NSTEPS</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.10000E-02 p012 DT</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p013 IOCOMM</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p014 IOTIME</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 250.000 p015 IOSTEP</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p016 PSSOLVER: 0=default</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p017</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.500000E-01 p018 GRID < 0 --> # cells on screen</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> -1.00000 p019 INTYPE</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 4.00000 p020 NORDER</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.100000E-06 p021 DIVERGENCE</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.100000E-08 p022 HELMHOLTZ</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 1 p23 NPSCAL</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.100000E-09 p024 TOLREL</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.100000E-04 p025 TOLABS</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 1.000000 p026 COURANT/NTAU</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 3.00000 p027 TORDER</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 1.00000 p028 TORDER: mesh velocity (0: p28=p27)</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p029 = magnetic visc if > 0, = -1/Rm if < 0</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p030 > 0 ==> properties set in uservp()</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p031 NPERT: #perturbation modes</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p032 #BCs in re2 file, if > 0</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p033</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p034</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p035</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p036</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p037</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p038</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p039</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p040</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p041 1-->multiplicative SEMG</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p042 0=gmres/1=pcg</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p043 0=semg/1=schwarz</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p044 0=E-based/1=A-based prec.</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p045 Relaxation factor for DTFS</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p046 reserved</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p047 vnu: mesh matieral prop.</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p048</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p049</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p050</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p051</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p052 IOHIS</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p053</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p054 fixed flow rate dir: |p54|=1,2,3=x,y,z</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p055 vol.flow rate (p54>0) or Ubar (p54<0)</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p056</p><p style="margin:0px;font-size:11px;font-family:Menlo">
0.00000 p057</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p058</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p059 !=0 --> full Jac. eval. for each el.</p><p style="margin:0px;font-size:11px;font-family:Menlo">
0.00000 p060 !=0 --> init. velocity to small nonzero</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p061</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p062 >0 --> force byte_swap for output</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p063 =8 --> force 8-byte output</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p064 =1 --> perturbation restart</p><p style="margin:0px;font-size:11px;font-family:Menlo">
0.00000 p065 #iofiles (eg, 0 or 64); <0 --> sep. dirs</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 6.00000 p066 output : <0=ascii, else binary</p><p style="margin:0px;font-size:11px;font-family:Menlo">
6.00000 p067 restart: <0=ascii, else binary</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 500.00000 p068 iastep: freq for avg_all (0=iostep)</p><p style="margin:0px;font-size:11px;font-family:Menlo">
0.00000 p069</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p070</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p071</p><p style="margin:0px;font-size:11px;font-family:Menlo">
0.00000 p072</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p073</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p074 verbose Helmholtz</p><p style="margin:0px;font-size:11px;font-family:Menlo">
0.00000 p075</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p076</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p077</p><p style="margin:0px;font-size:11px;font-family:Menlo">
0.00000 p078</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p079</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p080</p><p style="margin:0px;font-size:11px;font-family:Menlo">
0.00000 p081</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p082</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p083</p><p style="margin:0px;font-size:11px;font-family:Menlo">
0.00000 p084 !=0 --> sets initial timestep if p12>0</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p085 dt ratio if p84 !=0, for timesteps>0</p><p style="margin:0px;font-size:11px;font-family:Menlo">
0.00000 p086 reserved</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p087</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p088</p><p style="margin:0px;font-size:11px;font-family:Menlo">
0.00000 p089</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p090</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p091</p><p style="margin:0px;font-size:11px;font-family:Menlo">
0.00000 p092</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.0000 p093 Number of previous pressure solns saved</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p094 start projecting velocity after p94 step</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p095 start projecting pressure after p95 step</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p096</p><p style="margin:0px;font-size:11px;font-family:Menlo">
0.00000 p097</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p098</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 3.00000 p099 dealiasing: <0--> off/3--> old/4--> new</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p100</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p101 Number of additional modes to filter</p><p style="margin:0px;font-size:11px;font-family:Menlo">
1.00000 p102 Dump out divergence at each time step</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.05000 p103 weight of stabilizing filter (.01)</p><p style="margin:0px;font-size:11px;font-family:Menlo">
0.00000 p104</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p105</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p106</p><p style="margin:0px;font-size:11px;font-family:Menlo">
0.00000 p107 !=0 --> add to h2 array in hlmhotz eqn</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p108</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p109</p>
<p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p110</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p111</p><p style="margin:0px;font-size:11px;font-family:Menlo">
</p><p style="margin:0px;font-size:11px;font-family:Menlo"> 0.00000 p112</p></div><div><br></div></div>