Dear Konstantinos I understand the use of the Heaviside function but I do not get how you impose that the gravity is along the x axis
Thank you Regards AC From: Konstantinos Poulios <logar...@googlemail.com> Sent: Wednesday, November 17, 2021 1:37 AM To: Lesage,Anne Cecile J <ajles...@mdanderson.org> Cc: getfem-users@nongnu.org Subject: [EXT] Re: adding buoyancy forces to Biot poroelastic equations WARNING: This email originated from outside of MD Anderson. Please validate the sender's email address before clicking on links or attachments as they may not be safe. Dear Anne-Cecile, The GetFEM model object does not differentiate between left and right side of an equation (there is no reason for splitting equations like this), all equations are assumed to be in the form R(...)=0. So just move all terms on the same side. The equation you provide is in strong form, you need to convert it to the respective weak form and apply the necessary integration by parts to get rid of higher order derivatives as you showed in your add_linear_term expression. After all these steps you should have md.add_linear_term(mim9, 'G*Grad(u):Grad(Test_u)+G/(1-2*nu)*Div(u)*Div(Test_u)+(alpha*Grad(p)-g*(rho_tissue-rho_air*Heaviside(X(1))-rho_water*Heaviside(-X(1)))).Test_u') you can also choose to split the term in two lines md.add_linear_term(mim9, 'G*Grad(u):Grad(Test_u)+G/(1-2*nu)*Div(u)*Div(Test_u)') md.add_linear_term(mim9, '(alpha*Grad(p)-g*(rho_tissue-rho_air*Heaviside(X(1))-rho_water*Heaviside(-X(1)))).Test_u') but there is no reason for not keeping everything just in one term. BR Kostas On Tue, Nov 16, 2021 at 11:12 PM Lesage,Anne Cecile J <ajles...@mdanderson.org<mailto:ajles...@mdanderson.org>> wrote: Dear all To implement the building of my fem matrix for the mechanical equilibrium, I presently write md.add_linear_term(mim9, 'G*Grad(u):Grad(Test_u)+G/(1-2*nu)*Div(u)*Div(Test_u)+alpha*Grad(p).Test_u') How can i add an additional buoyancy terms to the equation (see right-hand side attached equation picture)? gravity is vector g = - 9180 N along the x axis for my mesh rhot (density tissue is constant) but rhof = rho water for x<0 and rhof = rho air for x>0 Thank you Anne-Cecile Lesage The information contained in this e-mail message may be privileged, confidential, and/or protected from disclosure. This e-mail message may contain protected health information (PHI); dissemination of PHI should comply with applicable federal and state laws. If you are not the intended recipient, or an authorized representative of the intended recipient, any further review, disclosure, use, dissemination, distribution, or copying of this message or any attachment (or the information contained therein) is strictly prohibited. If you think that you have received this e-mail message in error, please notify the sender by return e-mail and delete all references to it and its contents from your systems. The information contained in this e-mail message may be privileged, confidential, and/or protected from disclosure. This e-mail message may contain protected health information (PHI); dissemination of PHI should comply with applicable federal and state laws. If you are not the intended recipient, or an authorized representative of the intended recipient, any further review, disclosure, use, dissemination, distribution, or copying of this message or any attachment (or the information contained therein) is strictly prohibited. If you think that you have received this e-mail message in error, please notify the sender by return e-mail and delete all references to it and its contents from your systems.
