<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<!--[if !mso]><style>v\:* {behavior:url(#default#VML);}
o\:* {behavior:url(#default#VML);}
w\:* {behavior:url(#default#VML);}
.shape {behavior:url(#default#VML);}
</style><![endif]--><style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:"Century Gothic";
panose-1:2 11 5 2 2 2 2 2 2 4;}
@font-face
{font-family:Monaco;
panose-1:0 0 0 0 0 0 0 0 0 0;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:#0563C1;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:#954F72;
text-decoration:underline;}
pre
{mso-style-priority:99;
mso-style-link:"HTML Preformatted Char";
margin:0in;
margin-bottom:.0001pt;
font-size:10.0pt;
font-family:"Courier New";}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:"Calibri",sans-serif;
color:windowtext;}
span.HTMLPreformattedChar
{mso-style-name:"HTML Preformatted Char";
mso-style-priority:99;
mso-style-link:"HTML Preformatted";
font-family:"Courier New";}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri",sans-serif;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style>
</head>
<body lang="EN-US" link="#0563C1" vlink="#954F72">
<div class="WordSection1">
<p class="MsoNormal"><span style="font-size:11.0pt">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">I have been using blackbear (a moose framework app) to do a simple tensile test simulation on a complex material model with high amount of elements. I was able to get consistent and quick solution results
with low amount of elements, however once the amount of element start increasing, the solver won’t converge consistently and dt usually drops to a very low value, causing the simulation to run for a very long time. I am seeking recommendations for tips to
optimize the solver so I can get consistent and faster convergence rate. Here is the petsc option that I am using (along with SMP preconditioner):<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">l_max_its = 15<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">l_tol = 1e-8<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">nl_max_its = 50<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">nl_rel_tol = 1e-7<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">nl_abs_tol = 1e-9<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">petsc_options = '-snes_ksp_ew'<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">petsc_options_iname = '-pc_type -snes_linesearch_type'<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">petsc_options_value = 'lu bt'<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">end_time = 50.0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">dt = 0.5<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Here is a example output from the first few timesteps of the simulation:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">Time Step 2, time = 0.75, dt = 0.5</span><span style="font-size:8.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">0 Nonlinear |R| =
<span style="color:green">1.078014e-02</span></span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> 0 SNES Function norm 1.078014340559e-02</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> 0 Linear |R| =
<span style="color:green">1.078014e-02</span></span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> 0 KSP unpreconditioned resid norm 1.078014340559e-02 true resid norm 1.078014340559e-02 ||r(i)||/||b|| 1.000000000000e+00</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> 1 Linear |R| =
<span style="color:green">2.319831e-13</span></span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> 1 KSP unpreconditioned resid norm 2.319831277078e-13 true resid norm 2.255163534674e-13 ||r(i)||/||b|| 2.091960607412e-11</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Linear solve converged due to CONVERGED_RTOL iterations 1</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">NEML stress update failed!</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 1. is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">NEML stress update failed!</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 0.5 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">NEML stress update failed!</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 0.25 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">NEML stress update failed!</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 0.125 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">NEML stress update failed!</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 0.0625 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">NEML stress update failed!</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 0.03125 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 0.015625 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 0.0078125 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 0.00390625 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 0.00195312 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 0.000976562 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 0.000488281 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 0.000244141 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 0.00012207 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 6.10352e-05 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 3.05176e-05 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 1.52588e-05 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 7.62939e-06 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 3.8147e-06 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco;color:red"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 1.90735e-06 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 9.53674e-07 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 4.76837e-07 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 2.38419e-07 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco;color:red"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 1.19209e-07 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 5.96046e-08 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 2.98023e-08 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 1.49012e-08 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 7.45058e-09 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 3.72529e-09 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 1.86265e-09 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 9.31323e-10 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 4.65661e-10 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 2.32831e-10 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 1.16415e-10 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 5.82077e-11 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 2.91038e-11 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 1.45519e-11 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 7.27596e-12 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 3.63798e-12 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 1.81899e-12 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco"> Line search: objective function at lambdas = 9.09495e-13 is Inf or Nan, cutting lambda</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco">Nonlinear solve did not converge due to DIVERGED_LINE_SEARCH iterations 0</span><span style="font-size:8.0pt;font-family:"Courier New""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:Monaco;color:red">Solve Did NOT Converge!</span><span style="font-size:8.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">I really appreciate any inputs or insights, thanks for your time and help.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Best,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Sean<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<table class="MsoNormalTable" border="0" cellspacing="0" cellpadding="0" width="554" style="width:415.8pt;border-collapse:collapse">
<tbody>
<tr>
<td width="122" style="width:91.8pt;border:none;border-right:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt">
<p class="MsoNormal" align="center" style="text-align:center"><a href="https://kairospower.com/"><span style="font-size:11.0pt;font-family:"Arial",sans-serif;color:#464646;text-decoration:none"><img border="0" width="91" height="91" style="width:.9479in;height:.9479in" id="Picture_x0020_2" src="cid:image001.png@01D53B2C.98418C10" alt="signature_16346658"></span></a><span style="font-size:11.0pt"><o:p></o:p></span></p>
</td>
<td width="432" valign="top" style="width:4.5in;padding:0in 5.4pt 0in 5.4pt">
<p class="MsoNormal" style="margin-bottom:3.4pt"><b><span style="font-size:10.0pt;font-family:"Century Gothic",sans-serif;color:#323232">Sean Hsu</span></b><span style="font-size:9.0pt;font-family:"Century Gothic",sans-serif;color:#323232"> </span><span style="font-size:9.0pt;font-family:"Century Gothic",sans-serif;color:gray">Mechanics
of Materials Intern</span><span style="font-size:11.0pt"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:3.4pt"><span style="font-size:9.0pt;font-family:"Century Gothic",sans-serif;color:#595959">p</span><span style="font-size:9.0pt;font-family:"Century Gothic",sans-serif;color:#323232"> </span><span style="font-size:9.0pt;font-family:"Century Gothic",sans-serif;color:gray">510.808.5265</span><span style="font-size:9.0pt;font-family:"Century Gothic",sans-serif;color:#323232"> </span><span style="font-size:9.0pt;font-family:"Century Gothic",sans-serif;color:#595959"> e </span><span style="font-size:11.0pt"><a href="mailto:user@kairospower.com"><span style="font-size:9.0pt;font-family:"Century Gothic",sans-serif;color:#0563C1">hsu@kairospower.com</span></a></span><span style="font-size:9.0pt;font-family:"Century Gothic",sans-serif;color:#595959"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:3.4pt"><span style="font-size:9.0pt;font-family:"Century Gothic",sans-serif;color:gray">707 W Tower Ave, Alameda, CA 94501</span><span style="font-size:9.0pt;font-family:"Century Gothic",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><a href="http://www.kairospower.com"><b><span style="font-size:9.0pt;font-family:"Century Gothic",sans-serif;color:#0563C1">www.kairospower.com</span></b></a></span><span style="font-size:9.0pt;font-family:"Century Gothic",sans-serif;color:#E1750B"> </span><a href="https://www.linkedin.com/company/kairos-power-llc/"><span style="font-size:11.0pt;font-family:"Century Gothic",sans-serif;color:#0563C1;text-decoration:none"><img border="0" width="15" height="15" style="width:.1562in;height:.1562in" id="Picture_x0020_1" src="cid:image002.png@01D53B2C.98418C10" alt="Image result for linkedin logo"></span></a><span style="font-size:11.0pt"><o:p></o:p></span></p>
</td>
</tr>
</tbody>
</table>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
</body>
</html>