<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>