<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">
Hello,
<div class=""><br class="">
</div>
<div class="">I have a few questions on the turbChannel example.</div>
<div class=""><br class="">
</div>
<div class="">1) the ‘eddy viscosity ‘ is computed in the function eddy_visc and called in a loop over the elements of mesh 1. Inside the function eddy_visc there is the following piece of code:</div>
<div class=""><br class="">
</div>
<div class="">
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class="">
<i class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> if (e.eq.nelv) then ! planar avg and define nu_tau</span> </i></div>
</div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class="">
<i class=""> …</i></div>
<div style="margin: 0px; line-height: normal;" class="">
<div style="font-family: Menlo; font-size: 11px; margin: 0px; line-height: normal;" class="">
<span style="font-variant-ligatures: no-common-ligatures" class=""><i class=""> ntot = nx1*ny1*nz1*nelv</i></span></div>
<div style="font-family: Menlo; font-size: 11px; margin: 0px; line-height: normal;" class="">
<span style="font-variant-ligatures: no-common-ligatures" class=""><i class=""> do i=1,ntot</i></span></div>
<div style="font-family: Menlo; font-size: 11px; margin: 0px; line-height: normal;" class="">
<span style="font-variant-ligatures: no-common-ligatures" class=""><i class=""> cdyn = 0</i></span></div>
<div style="font-family: Menlo; font-size: 11px; margin: 0px; line-height: normal;" class="">
<span style="font-variant-ligatures: no-common-ligatures" class=""><i class=""> if (den(i,1).gt.0) cdyn = 0.5*num(i,1)/den(i,1)</i></span></div>
<div style="font-family: Menlo; font-size: 11px; margin: 0px; line-height: normal;" class="">
<span style="font-variant-ligatures: no-common-ligatures" class=""><i class=""> cdyn = 0.16*0.16 ! max(cdyn,0.) ! AS ALTERNATIVE, could clip ediff</i></span></div>
<div style="font-family: Menlo; font-size: 11px; margin: 0px; line-height: normal;" class="">
<span style="font-variant-ligatures: no-common-ligatures" class=""><i class=""> ediff(i,1) = param(2)+cdyn*dg2(i,1)*snrm(i,1)</i></span></div>
<div style="font-family: Menlo; font-size: 11px; margin: 0px; line-height: normal;" class="">
<span style="font-variant-ligatures: no-common-ligatures" class=""><i class=""> enddo</i></span></div>
<div style="font-family: Menlo; font-size: 11px; margin: 0px; line-height: normal;" class="">
<span style="font-variant-ligatures: no-common-ligatures" class=""><i class=""> endif</i></span></div>
<div style="font-family: Menlo; font-size: 11px; margin: 0px; line-height: normal;" class="">
<span style="font-variant-ligatures: no-common-ligatures" class=""><i class=""><br class="">
</i></span></div>
<div style="font-family: Menlo; font-size: 11px; margin: 0px; line-height: normal;" class="">
<span style="font-variant-ligatures: no-common-ligatures" class="">eddy that stores the eddy viscosity is updated when the last element of mesh 1 is called. Is there any reason why it should be done in this manner?</span></div>
<div style="font-family: Menlo; font-size: 11px; margin: 0px; line-height: normal;" class="">
<span style="font-variant-ligatures: no-common-ligatures" class=""><br class="">
</span></div>
<div style="font-family: Menlo; font-size: 11px; margin: 0px; line-height: normal;" class="">
<span style="font-variant-ligatures: no-common-ligatures" class="">2) I am still confused over the differences between ‘ifsplit’, ‘ifexplvis’ and ‘ifstrs’. From the archive and the documentation I understand the following (please correct me if I am wrong):</span></div>
<div style="margin: 0px; line-height: normal;" class="">
<ul class="MailOutline">
<li class=""><font face="Menlo" class=""><span style="font-size: 11px;" class="">‘ifexplvis’ is set to true when the user specified the viscosity coefficient in uservp. It does not required, however, the stress formation meaning the the diffusive term in the
NS equations looks like \mu(x,t) \nabla^2 \vec{u}.</span></font></li><li class=""><font face="Menlo" class=""><span style="font-size: 11px;" class="">when ‘ifsplit’ is set to true, the viscosity is split in a explicit part and an implicit part. If this correct, how and where are defined the explicit and implicit parts?</span></font></li><li class=""><font face="Menlo" class=""><span style="font-size: 11px;" class="">‘ifstrs’: when set to true, ‘ifexplvis’ and ‘if split’ do not have any effect.</span></font></li></ul>
<div class=""><font face="Menlo" class=""><span style="font-size: 11px;" class=""><br class="">
</span></font></div>
<div class=""><font face="Menlo" class=""><span style="font-size: 11px;" class="">3) could someone shed some light on the subroutine ‘set_ds_filt’ in turbChannel.usr, please? It seems to compute some sort of filter that is then used to compute M_{i,j} and L_{i,j}</span></font></div>
<div class=""><font face="Menlo" class=""><span style="font-size: 11px;" class=""><br class="">
</span></font></div>
<div class=""><font face="Menlo" class=""><span style="font-size: 11px;" class=""><br class="">
</span></font></div>
<div class=""><font face="Menlo" class=""><span style="font-size: 11px;" class="">Thanks,</span></font></div>
<div class=""><font face="Menlo" class=""><span style="font-size: 11px;" class="">Marco</span></font></div>
<div class=""><font face="Menlo" class=""><span style="font-size: 11px;" class=""><br class="">
</span></font></div>
</div>
</div>
</body>
</html>