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Emmanuelle Fergon

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  1. Hi, I've modeled a geometry on HyperMesh and i've exported it as a Parasolied (.x_t file) and now i want to import the geometry on AcuSolve in order to run a CFD analysis. And the import of the geometry on AcuSolve doesn't systematically work, and I don't knwo why. The problem is that i don't manage to find the reason why it doesn't work systematically. I've tried also .nas and .cas files, and it doesn't wor at all. I got this type of error : Could you please tell me steps to export the good type of file that can be read with AcuSolve. It would be really nice!! Or just tell me the reason why i can't manage to import any files on AcuSolve. Yours, Emmanuelle
  2. Hi, I'd like to model a box floating in open water, that means that wave generation and especially wave absorption should be modelised. I've modeled this on Hypermesh with the solver Radioss In this model, there are 2 sorts of interaction : - fluid/fluid : air with water - fluid/structure : both fluids with the box. First, I've used an ALE model for the fluids. I've tried to use both MAT/LAW51 (multimaterial) and MAT/LAW37 (biphasic material) in order to model this, but everytime there is a leakage and the computation can't run until the end (negative rho error). I've also tried to use MAT/LAW11 (bound) because it doesn't work properly with a biphasic material (negative rho error). Then, I've tried with an SPH model with IN and OUT condition, so that the computaiton doesn't take into account the air/water interaction, the computation also stops because of a leakage. For the fluid/structure interaction, I've used INTER/TYPE18 and INTER/TYPE7 respectively for ALE and SPH model. I have to set a STfval value for the stiffness. I use the formula of the Help page : stfval=rho*v²*A_el/GAP = 66.667avec - rho=rho_water = 0.001g/mm3; - v=10 mm/ms , initial velocity of the box when it is dropped in the water; - A_el = lagragien element surface =500 * 500 mm² ; - GAP= 1.5 * E_el = 1.5 * 250 = 375mm With this value, the box is floating in the air, the only way i've found a value that models reality was by dichotomy.. That's not convenient for further simulation with different initial data.... Should you have any suggestion to model an infinite water volume (so wave absorption) and for the stiffness value, please contact me. Sincerly yours, Emmanuelle
  3. Hi Georges P Johnson, Thank you very much for your answer. I've double-checked the contact definition, the material properties and unites, and everything seems well set. Moreover I've tried to use the similar parameters as in the case study (initial gas pressure at 1e-20), the results show that the pressure gradient in the water doesn't appear anymore. I've also tried to use INTER/TYPE1, but the problem is that the nodes on the faces have already several boundary conditions because of the outlet conditions, so the computation can't run. Dhould you have any other suggestion, please let me know. Thanks again
  4. Hi, I'm trying to simulate the interraction between a box and waves in the sea. Thus I'm using the material LAW37 (BIPHAS) in order to model the interface between water and air which are modeled in ALE. The problem is that I don't know how to model the boundary conditions on the transverse faces in order to avoid wave reflexions on the wall (to simplify the computation, all DoFs are fixed on the longitudinal faces). I can't use MAT/BOUND (LAW11) because it doesn't work properly with the LAW37. So i'm trying to model these boundary conditions using a material LAW37 to create an "air outlet" and a "water outlet" with the same initial values as air except for : -the liquid bulk modulus C_Liquid = 0.0 - gamma = 0.0 The computation runs well at the beginning and i get a pressure gradient in the fluid volume, so it's okay. But then an error appears : " STOP : NEGATIVE RHO=-0.1322538772563E-09 FOR 3D-ELEMENT ID=3696 ERROR TERMINATION " In the results file I can see that there is a problem with a really big velocity vector on top of the volume in the air part. I think this is linked, but I don't know how to avoid this. Moreover, to model the interface between the box and the water, I use INTER/TYPE18 but I don't know how to set the right value for the StfVal. Using the formula written in the Hyperworks Help i.e. StfVal=(rho * v² * Sel)/GAP , the box is floating in the air, and not in the water. Do you have any suggestion? Thank you very much in advance, Hereby the .rad file ALE_05a_0000.rad
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