<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi Wolfgang,<div><br></div><div>Thank you for the reply and yes, I agree with everything below in terms of the units.</div><div><br></div><div>In order to prevent any confusion from future users reading the output, I would do one of two things:</div><div>1) Change the output value to the actual heat flux W/m (2D) or W/m2 (3D)</div><div>or </div><div>2) Change the description of the output values from "heat flux" to "total heat output across boundary" (or something along those lines).</div><div><br></div><div>I think option 1) would be preferable as I imagine most users would want the heat flux.</div><div><br></div><div>Does anyone else have an opinion or preference on this?</div><div><br></div><div>Cheers,</div><div>John</div><div><br></div><div><div><div><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><br class="Apple-interchange-newline"></span><br class="Apple-interchange-newline"></div></span></span>
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<br><div><div>On Jun 26, 2012, at 2:25 AM, Wolfgang Bangerth wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div><br><blockquote type="cite">Thanks for the quick reply! From heat_flux_stastics.cc (lines 96-103)<br></blockquote><blockquote type="cite">there is<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">local_normal_flux<br></blockquote><blockquote type="cite">+=<br></blockquote><blockquote type="cite">-thermal_conductivity *<br></blockquote><blockquote type="cite">(temperature_gradients[q] *<br></blockquote><blockquote type="cite">fe_face_values.normal_vector(q)) *<br></blockquote><blockquote type="cite">fe_face_values.JxW(q);<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Is this the equation you are referencing below? If it is, I'm not sure<br></blockquote><blockquote type="cite">what normal_vector(q) and JxW refer to. Is normal_vector(q) a<br></blockquote><blockquote type="cite">directional multiplier?<br></blockquote><br>This formula is the numerical approximation to the integral<br><br> \int_{\Gamma_i} - k nabla T . n dS<br><br>that Timo referenced. Here, n=normal_vector(q) at quadrature point q, <br>has no physical units, and JxW(q)=area element dS has units meters in <br>2d and meters^2 in 3d. Gamma_i is the part of the boundary of the <br>domain with boundary indicator i.<br><br>k, the thermal conductivity, is documented as having units W/m/K, so in <br>3d I indeed get units W for the entire expression. (Timo: The <br>derivative has units K/m, not K/s.) That is exactly the (integrated) <br>heat flux through the surface we were looking for.<br><br>John: Do you agree? This may of course not be what you need from a <br>simulation -- if so, let us know what it is that you want and we can see <br>how to implement it.<br><br>Cheers<br> W.<br><br>PS: The units of the conductivity are<br> heat flux per unit area perpendicular to the flux direction<br> - per -<br> unit gradient in temperature<br>In 3d, that is (W/m^2) / (K/m) = W/(K m) as documented. In 2d, on the <br>other hand, it is (W/m) / (K/m) = W/K. In other words, in 2d, the <br>units of the above formula would be<br> W/K * K/m * 1 * m<br>which is again just Watts. I've fixed the description of the units in <br>the documentation to this end.<br><br>------------------------------------------------------------------------<br>Wolfgang Bangerth email: <a href="mailto:bangerth@math.tamu.edu">bangerth@math.tamu.edu</a><br> www: <a href="http://www.math.tamu.edu/~bangerth/">http://www.math.tamu.edu/~bangerth/</a><br><br>_______________________________________________<br>Aspect-devel mailing list<br><a href="mailto:Aspect-devel@geodynamics.org">Aspect-devel@geodynamics.org</a><br>http://geodynamics.org/cgi-bin/mailman/listinfo/aspect-devel<br></div></blockquote></div><br></div></div></body></html>