<div dir="ltr">There's no general way to compute gradients normal to the surface so you need to compute the gradient on the simulation's cells (e.g. volumetric cells for 3D). You can use the Gradient Of Unstructured Data set to do that. Then extract the surface as Mathi said, use the Normals filter to compute the normals, use the Calculator filter to multiply the normals by the gradient and the viscosity and you'll have the wall shear stress over the entire boundary surface. You can then select the cells you want to show the WSS over the exact portion of the desired boundary.<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Dec 6, 2017 at 9:05 AM, Ezhilmathi Krishnasamy <span dir="ltr"><<a href="mailto:ezhkr601@student.liu.se" target="_blank">ezhkr601@student.liu.se</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div><div><div><div>Hi Ahmet, <br><br></div>What you can do that is, use the filter name called extract surface. <br></div>once you get that surface either you can export those values in form of from elements or from the points.<br><br></div>It might work, or you may get more clear explanation from this forum.<br><br></div>Cheers, <br></div>Mathi <br><div><div><div><br><br></div></div></div></div><div class="gmail_extra"><br><div class="gmail_quote"><div><div class="h5">On 6 December 2017 at 15:00, Ahmet Ahmet <span dir="ltr"><<a href="mailto:ahmetskyland@gmail.com" target="_blank">ahmetskyland@gmail.com</a>></span> wrote:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5"><div dir="ltr"><div dir="ltr"><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:small;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;display:inline;float:none">Hello everyone,</span><div style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:small;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial"><br></div><div style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:small;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial"><div>I
have results with OpenFOAM including p,T,U outputs. Due to some
reasons, I can't use wallShearStress or wallgradU utility in OF. So, I
have to calculate it on Paraview. I saw many topics related to that on
google, but I could not find a satisfactory answer. My case is 3-D,
compressible and laminar but we can think about incompressible and may
be 2-D. </div><div><br></div><div>I think the most important part for
WSS is to calculate velocity gradient. My unsolved problem is to
calculate that. How can I calculate gradients on the wall? I have
no-slip wall, that is u=0 and with<span> </span><b>Gradient of Unstructured DataSet/Compute Derivatives </b>filters,
I obtained 0 on the wall. I think the values in the nearest mesh to the
wall should be accounted for. To do that, what should I do?</div><div><br></div><div><b>Note:</b> <br></div><div><ol><li>T<span style="color:rgb(0,0,0);white-space:pre-wrap">he walls are not aligned with a coordinate axis. For this part, I tried to </span><span style="color:rgb(0,0,0);white-space:pre-wrap">extract the wall surface and generate normal vectors. <br></span></li><li><span style="color:rgb(0,0,0);white-space:pre-wrap">As an alternative to get directly on wall, I tried to get slice a little bit over the wall surface and then take surface vector on slice then gradient of unstructured dataset on surface vector. That gives me a result but I am not sure it's true. </span></li></ol></div><div><br></div><div>This may be simple for you, sorry for that.</div><div>Thank you in advance,</div></div><div style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:small;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;text-decoration-style:initial;text-decoration-color:initial"><div><div class="m_4323291488164568649m_-2537045137127734915gmail-m_4416169094697429070gmail_signature">Ahmet</div></div></div></div></div>
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