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tractionDisplacement BC for solidDisplacementFoam with Body ForcesHi Foamers,
I need to add body forces to the solidDisplacementFoam solver. So it goes something similar to: Code:
`fvVectorMatrix DEqn` bodyForces vectorField represents accelerations (e.g. gravity). Nevertheless, I have not found a reference on how to add a term to gradient() in tractionDisplacement boundary condition. I mean that for example a term for strain resulting from thermal stresses is added to the gradient() in tractionDisplacementFvPatchVectorField.C like:Code:
`gradient() =` Best regards, Hisham El Safti |

Quote:
Body forces act on the volume of each cell and are source terms so they do not have boundary conditions. So to add a body force term, just add 'rho*g' to the momentum equation, where g is a dimensionedVector -9.81 in the y direction. Philip |

Hi Philip
Quote:
I also have some other explicit terms that come from another variable (pore fluid velocity). They are all explicit terms (as the case of the "T" term in the DEqn in solidDisplacementFoam.C) Code:
` if (thermalStress)` tractionDisplacement BC] due to the existence of a "T" BC or because "T" contributes to the displacement gradient?Best regards, Hisham |

Hi Hisham,
The reason there is a T-term in the boundary condition is because T appears in the constitutive equation i.e. Hooke's law for a thermal elastic solid is: sigma =2*mu*e +lambda*I*tr(e) - (2*mu + 3*lambda)*alpha*(T - Tref)*I Therefore the traction on a boundary face is Trac = n . sigma, and then you sub in Hooke's law and rearrange this equation to get the equivalent (implicit) gradient on the boundary, which is what you set in the traction BC. So the traction BC will contain a T-term. But it will not contain any body force contributions. If you add rho*g to the momentum equation then it will work, I ran a quick test case and everything is fine on the traction boundaries. Philip |

Hi Philip
Thanks a lot for your help! Now it is clear to me :) Best regards Hisham |

Hi Philip
using the same methodology, if simulation fluid-structure interaction problem, and i want to transfer the temperature computed at the wall of a solid, as boundary condition for the fluid part (where there is a common patch between fluid and solid) ?? Best regards |

Quote:
yes you can follow the same Dirichlet-Neumann coupling procedure to couple the temperature between the regions. Philip |

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