<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style type="text/css" style="display:none;"><!-- P {margin-top:0;margin-bottom:0;} --></style>
</head>
<body dir="ltr">
<div id="divtagdefaultwrapper" style="font-size:12pt;color:#000000;font-family:Calibri,Helvetica,sans-serif;" dir="ltr">
<p style="margin-top:0;margin-bottom:0">I am using FLASH4.4. I am running a 2D simulation in cylindrical coordinates using the MHD staggered mesh solver and a uniform grid. My simulation will run for about 30 seconds (simulation time) then it crashes. The error
I get can vary based on the cfl and minimum time step I give it, but the issue is that the y momentum begins to sharply decrease and then the Kinetic energy jumps significantly and the run crashes.
<br>
</p>
<p style="margin-top:0;margin-bottom:0"><br>
</p>
<p style="margin-top:0;margin-bottom:0">Here is part of an output file for one of the runs:</p>
<p style="margin-top:0;margin-bottom:0"><br>
</p>
<p style="margin-top:0;margin-bottom:0">This run had a cfl condition of .2, and a minimum time step of 1e-6 seconds.<br>
</p>
<p style="margin-top:0;margin-bottom:0"><span> time y-momentum E_kinetic E_internal MagEnergy
<br>
</span></p>
<p style="margin-top:0;margin-bottom:0"></p>
<div> 3.165470637854052782E+01 5.587253776952739325E+30 4.753600339710994969E+49 8.743916647261655525E+49 1.754228010830377560E+42<br>
3.165493812157636455E+01 4.754893533206718301E+30 4.754122794831045632E+49 8.743926772696261717E+49 1.754446232246603526E+42<br>
3.165493813157636538E+01 2.596391772160589512E+26 4.979926949539627564E+49 8.743926773126580588E+49 1.754485014199999339E+42<br>
3.165493814157636621E+01 1.616370861886859215E+26 7.629586798455982783E+54 8.743926773725260724E+49 1.778462439566404185E+42<br>
<br>
The error given for this is: <br>
<br>
<div>[eos_helm] Negative total pressure.<br>
values: dens,temp: 471500237.463805 5.857646036122962E+015 <br>
<br>
values: abar,zbar: 14.1176470588276 7.05882352941380 <br>
<br>
coulomb coupling parameter Gamma: 6.231188937874524E-007 <br>
<br>
Prad 2.96915E+48 Pion 1.62660E+31 Pele -4.17392E+49 Pcoul 0.00000E+00 <br>
<br>
Ptot -3.87700E+49 df_d -7.51000E+32 <br>
<br>
DRIVER_ABORT: [eos_helm] ERROR: negative total pressure.<br>
</div>
<br>
<br>
On similar runs I have gotten errors suggesting lowering the cfl condition and something about needing a finer grid.
<br>
<br>
I am not sure what is going on to cause this issue. I have also tried increasing cvisc but it still crashes. Any help figuring out what is causing this issue would be greatly appreciated.
<br>
<br>
Malia Jenks<br>
</div>
<br>
<p></p>
</div>
</body>
</html>