<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head>
<meta content="text/html; charset=UTF-8" http-equiv="Content-Type"/>
</head><body>
<p style="margin: 0px;"><span><span></span></span><a href="mailto:michael.asam@infineon.com">michael.asam@infineon.com</a> hat am 6. August 2012 um 11:55 geschrieben:<br/><br/>> Hi Jochen,<br/>> <br/>> sorry for the late response.<br/>> The deviation is due to an inadequate mesh-size because the characteristic<br/>> length varies linearly between the two electrodes, whereas the E field is<br/>> proportional to r^-2.<br/>> So the best is to use a field in Gmsh to specify the mesh size by<br/>> an equation, or in case of more complex geometries do adaptive meshing.<br/>> <br/>> Please find attached a modification of your example for adaptive meshing.<br/>> As your geometry is axisymmetrical I've reduced it to 2D.<br/>> Just generate a mesh with Gmsh as usual and run GetDP. Do the post-<br/>> processing "GenerateAdaptionFile" and plot it in Gmsh.<br/>> There do a right click in the main window on the according view number<br/>> and choose "Apply As Background Mesh" and then mesh the geometry<br/>> once again.<br/>> With the adapted mesh size the result should be better.<br/>> For 3D the procedure should be similar.<br/>> <br/>> I hope this is of some help.<br/>> <br/>> Kind regards,<br/>> Michael<br/>></p>
<p style="margin: 0px;"> </p>
<p style="margin: 0px;">Dear Michael,</p>
<p style="margin: 0px;"> </p>
<p style="margin: 0px;">thanks for your help!</p>
<p style="margin: 0px;">Using your adaptive meshing example (2D), deviation from the analytical result can be decreased from 0,05% with linear variation of mesh size to 0,006% with applied adaptive meshing.</p>
<p style="margin: 0px;">But when I transferred this procedure to my 3D problem, the deviation stayed at approx. 5%. What I had to do, was decreasing the outer radius from 200 m to 50 m and modeling just one quarter of the hemisphere to get more elements per volume (see attached files). with approx. 600000 elements, I get a deviation of 1,03%, which can be decreased by adaptive meshing to 0,94%.</p>
<p style="margin: 0px;">Now my RAM is on its limit (32 Bit Win7). Are there any other ways to increase the accuracy without increasing the element size?</p>
<p style="margin: 0px;"> </p>
<p style="margin: 0px;">Greetings,</p>
<p style="margin: 0px;"> </p>
<p style="margin: 0px;">Jochen</p>
</body></html>