<div dir="ltr">Hello,<div><br></div><div>My problem is common, i'd like to solve the heat equation with, for example, 2 natural Robin BC and one adibatique BC : -lambda.dnT = h.(T-Ti) on Gamma_i with i={1,2} and lambda.dnT = 0 on Gamma_3. </div><div>I write the weak form with u in Form0 of the heat equation leads to the classical form :</div><div><div><br></div><div></div></div><div class="prettyprint" style="border: 1px solid rgb(187, 187, 187); word-wrap: break-word; background-color: rgb(250, 250, 250);"><code class="prettyprint"><div class="subprettyprint"><span style="color: #606;" class="styled-by-prettify">Equation</span><span style="color: #660;" class="styled-by-prettify">{</span><span style="color: #000;" class="styled-by-prettify"><br>      </span><span style="color: #606;" class="styled-by-prettify">Galerkin</span><span style="color: #660;" class="styled-by-prettify">{</span><span style="color: #000;" class="styled-by-prettify"> </span><span style="color: #660;" class="styled-by-prettify">[</span><span style="color: #008;" class="styled-by-prettify">lambda</span><span style="color: #660;" class="styled-by-prettify">[]</span><span style="color: #000;" class="styled-by-prettify"> </span><span style="color: #660;" class="styled-by-prettify">*</span><span style="color: #000;" class="styled-by-prettify"> </span><span style="color: #606;" class="styled-by-prettify">Dof</span><span style="color: #660;" class="styled-by-prettify">{</span><span style="color: #606;" class="styled-by-prettify">Grad</span><span style="color: #000;" class="styled-by-prettify"> u</span><span style="color: #660;" class="styled-by-prettify">},</span><span style="color: #000;" class="styled-by-prettify"> </span><span style="color: #660;" class="styled-by-prettify">{</span><span style="color: #606;" class="styled-by-prettify">Grad</span><span style="color: #000;" class="styled-by-prettify"> u</span><span style="color: #660;" class="styled-by-prettify">}];</span><span style="color: #000;" class="styled-by-prettify"><br>        </span><span style="color: #606;" class="styled-by-prettify">In</span><span style="color: #000;" class="styled-by-prettify"> </span><span style="color: #606;" class="styled-by-prettify">Omega</span><span style="color: #660;" class="styled-by-prettify">;</span><span style="color: #000;" class="styled-by-prettify"> </span><span style="color: #606;" class="styled-by-prettify">Jacobian</span><span style="color: #000;" class="styled-by-prettify"> </span><span style="color: #606;" class="styled-by-prettify">JVol</span><span style="color: #660;" class="styled-by-prettify">;</span><span style="color: #000;" class="styled-by-prettify"> </span><span style="color: #606;" class="styled-by-prettify">Integration</span><span style="color: #000;" class="styled-by-prettify"> I1</span><span style="color: #660;" class="styled-by-prettify">;}</span><span style="color: #000;" class="styled-by-prettify"><br>   <br>  </span><span style="color: #606;" class="styled-by-prettify">Galerkin</span><span style="color: #660;" class="styled-by-prettify">{</span><span style="color: #000;" class="styled-by-prettify"> </span><span style="color: #660;" class="styled-by-prettify">[</span><span style="color: #000;" class="styled-by-prettify"> h</span><span style="color: #660;" class="styled-by-prettify">[]*</span><span style="color: #000;" class="styled-by-prettify"> </span><span style="color: #660;" class="styled-by-prettify">(</span><span style="color: #606;" class="styled-by-prettify">Dof</span><span style="color: #660;" class="styled-by-prettify">{</span><span style="color: #000;" class="styled-by-prettify">u</span><span style="color: #660;" class="styled-by-prettify">}</span><span style="color: #000;" class="styled-by-prettify"> </span><span style="color: #660;" class="styled-by-prettify">-</span><span style="color: #000;" class="styled-by-prettify"> T</span><span style="color: #660;" class="styled-by-prettify">[]),</span><span style="color: #000;" class="styled-by-prettify"> </span><span style="color: #660;" class="styled-by-prettify">{</span><span style="color: #000;" class="styled-by-prettify">u</span><span style="color: #660;" class="styled-by-prettify">}];</span><span style="color: #000;" class="styled-by-prettify"><br>       </span><span style="color: #606;" class="styled-by-prettify">In</span><span style="color: #000;" class="styled-by-prettify"> </span><span style="color: #606;" class="styled-by-prettify">Ambiance</span><span style="color: #660;" class="styled-by-prettify">;</span><span style="color: #000;" class="styled-by-prettify"> </span><span style="color: #606;" class="styled-by-prettify">Jacobian</span><span style="color: #000;" class="styled-by-prettify"> </span><span style="color: #606;" class="styled-by-prettify">JSur</span><span style="color: #660;" class="styled-by-prettify">;</span><span style="color: #000;" class="styled-by-prettify"> </span><span style="color: #606;" class="styled-by-prettify">Integration</span><span style="color: #000;" class="styled-by-prettify"> I1</span><span style="color: #660;" class="styled-by-prettify">;}</span><span style="color: #000;" class="styled-by-prettify"><br></span><span style="color: #660;" class="styled-by-prettify">}</span></div></code></div><div><br></div><div><br></div><div>In my problem there is no essential BC so i do not have Constraint block.</div><div>The computation give a 0 temperature field, I do not understand what's wrong.</div><div><br></div><div>Moreover : </div><div>1 - I wan to store in a file the temperature field respects to the nodes but PostOperation block computes over elements.</div><div>2 - How can I compute the integral of the flux over Gamma_i, to do so, I need for each boundary edge : the flux and the normal vector</div><div><br></div><div>Best regards.</div></div>