<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><font class="Apple-style-span" color="#1D00FF">Hi Walter,</font></div><div><font class="Apple-style-span" color="#1D00FF"><br></font></div><div><font class="Apple-style-span" color="#1D00FF">Thank you for your help. I just had a few questions about what you sent.</font></div><div><br></div><br><div><div><blockquote type="cite">Hi,<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">I am having difficulty with the static vs. wrap top boundary setting,<br></blockquote><blockquote type="cite">the hydrostatic top BC, and a static side boundary setting. I am<br></blockquote><blockquote type="cite">trying to simulate a vertical subduction zone, so that the velocity<br></blockquote><blockquote type="cite">along the left edge is Vy = -Vslab and Vx=0. I would like to keep the<br></blockquote><blockquote type="cite">top of the simulation flat, so Vy=0 and the left and bottom just a<br></blockquote><blockquote type="cite">hydrostatic pressure condition (as to simulate an infinite domain).<br></blockquote><br>If you set Vy=0 on the top, then that will, by itself, force the top<br>to be flat.<br><br>As for your other questions:<br><br>1) Hydrostatic BC<br><br> If you add a HydrostaticTerm, then you should always add a<br> hydrostatic BC. This is independent of whether you use static or<br> wrap top.<br><br>2) Static Top<br><br> You would generally use this only if you have something like an air<br> layer. That is, you have a material on top with negligible mass.<br> This is so that you do not have to simulate the entire atmosphere,<br> which does not affect your simulation anyway.<br><br>3) Wrap Top<br><br> This is what you usually want to use on the top.<br><br>In your case, you are setting Vy=0 on the top. That should give<br>identical results for static top and wrap top, except at the left<br>side, where Vy=-Vslab. In fact, since you are specifying Vy=0, you do<br>not need to specify either static top or wrap top.<br><br>My guess is that what you really want is a static left as well. That<br>will fix the top and bottom left corners.<br><br>Also, I noticed that, in your input file, you specified the left BC<br>after the top BC. The corner is set by whatever comes last, so it<br>seems that you added a fixedCornerShape to set it back to zero. You<br>may want to switch that. I am attaching a new input file that does<br>what I think you want and a screenshot after 20 steps.</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span><font class="Apple-style-span" color="#1900FF">~ The picture you attached looks like what I'm trying to do, but I can't seem to open the input file you attached.</font></div><div><br>Note if you set Vy=0 on the top and Vy=-Vslab on the left, then you<br>will have a step function in the velocity at the corner. To solve<br>Stokes flow, we have to take a derivative of the velocity, resulting<br>in a delta function.<br><br>Numerical codes do not like delta functions. It may not be entirely<br>fatal. The Geomod 2004 shortening experiment, for example, has a step<br>function at the corner. But it does make it difficult to get reliable<br>results. If you have an analytic solution for the corner flow, it may<br>help to specify that directly.<br><br></div><div><span class="Apple-tab-span" style="white-space:pre"><font class="Apple-style-span" color="#2821FF"> </font></span><font class="Apple-style-span" color="#2821FF">~ How would I specify a corner flow solution directly?</font></div><div><br>Cheers,<br>Walter Landry</div></div><br><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"><font class="Apple-style-span" color="#2B0DFF"> </font></span><font class="Apple-style-span" color="#2B0DFF">Thank you,</font></div><div><span class="Apple-tab-span" style="white-space:pre"><font class="Apple-style-span" color="#2B0DFF"> </font></span><font class="Apple-style-span" color="#2B0DFF">Karen</font></div></body></html>