<div dir="ltr"><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)">Good morning,</div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)">I would like to start by thanking you for creating such a great software and distributing it for free.</div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)">I intend to use to it perform calculations on linear elasticity.</div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)">To illustrate my question, I will use a simple example: </div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)">Let's say I want to compute the stress that arises inside a tube when it is subjected to an internal pressure.</div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)">I have created the mesh on gmsh by creating two cylinders and substracting them, giving rise to a tube. Then I have defined the inner wall of the tube as a physical surface.</div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)">I am following one of the tutorials provided with GetDp, in particular the file wrench2D.pro</div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)">When it comes to defining the pressure acting on the surface, the file says:</div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><span style="margin:0px;padding:0px;border:0px;font:inherit;vertical-align:baseline;color:inherit">Integral { [ pressure_x[] , {ux} ];<br></span><span style="margin:0px;padding:0px;border:0px;font:inherit;vertical-align:baseline;color:inherit">        In Sur_Force_Mec ; Jacobian Sur ; Integration Gauss_v ; }</span><br></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><span style="margin:0px;padding:0px;border:0px;font:inherit;vertical-align:baseline;color:inherit"><br></span></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><span style="margin:0px;padding:0px;border:0px;font:inherit;vertical-align:baseline;color:inherit">Because in that case the pressure was acting in the x direction. However, in my case, the pressure is not acting in a defined direction, but normally to a surface.</span></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><span style="margin:0px;padding:0px;border:0px;font:inherit;vertical-align:baseline;color:inherit"><br></span></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><span style="margin:0px;padding:0px;border:0px;font:inherit;vertical-align:baseline;color:inherit">How can I translate this equation to take into account pressures acting normally against a surface with an arbitrary shape?</span></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><span style="margin:0px;padding:0px;border:0px;font:inherit;vertical-align:baseline;color:inherit"><br></span></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><span style="margin:0px;padding:0px;border:0px;font:inherit;vertical-align:baseline;color:inherit">Do I have to change other parts of the code?</span></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><span style="margin:0px;padding:0px;border:0px;font:inherit;vertical-align:baseline;color:inherit"><br></span></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><span style="margin:0px;padding:0px;border:0px;font:inherit;vertical-align:baseline;color:inherit">Thanks in advance.</span></div><div style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:12pt;line-height:inherit;font-family:Calibri,Arial,Helvetica,sans-serif;vertical-align:baseline;color:rgb(0,0,0)"><br></div></div>