<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>You can also try error function like profile with 0 value at the inlet and increases to a peak somewhere and stays constant up to the exit so gradient is0 at the exit<br>Insulation normally refers to the diffusive flux (first form)</div><div>Ammar</div><div><br>Sent from my iPhone</div><div><br>On Oct 12, 2013, at 11:50 PM, <a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.gov</a> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr"><div class="gmail_extra">Yes Ammar, I get oscillatory solutions with the discontinuous bc. I will try your suggestion.</div><div class="gmail_extra"><br></div><div class="gmail_extra" style="">When we specify insulated bc 'I' for an advected-diffused scalar c, does it make</div>
<div class="gmail_extra" style=""><br></div><div class="gmail_extra" style="">grad(c).n = 0 </div><div class="gmail_extra" style=""><br></div><div class="gmail_extra" style="">or</div><div class="gmail_extra" style=""><br></div><div class="gmail_extra" style="">
(u.n)c - D*grad(c).n = 0</div><div class="gmail_extra" style=""><br></div><div class="gmail_extra" style="">If I want to implement the second case, what should I do ?</div><div class="gmail_extra" style=""><br></div><div class="gmail_extra" style="">
Thanks</div><div class="gmail_extra" style="">praveen</div><div class="gmail_extra" style=""><br></div><div class="gmail_extra"><div><br></div><div><br></div><div class="gmail_quote">On Sun, Oct 13, 2013 at 10:11 AM, <span dir="ltr"><<a href="mailto:nek5000-users@lists.mcs.anl.gov" target="_blank">nek5000-users@lists.mcs.anl.gov</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div>The c=0 bc Is not consistent with the initial condition. You are generating a big error at t=0 that persists throughout your simulation. My understanding is you want to simulate the dispersion of a scalar that is already injected in a flow at t=0 right? I would spatially localize the concentration so that it decays to 0 at the inflow boundary ..a Gaussian exp(- x-a)^2) is a good candidate for your initial conditions </div>
<div>Ammar<br></div></blockquote></div><br><br></div></div>
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