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Showing results for tags 'mfluid'.
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Hello, I would like to setup MFLUID bulk data card in Nastran using Hypermesh. In optistruct a contact surface can be used to set the wetted elements on the structure. However in the Nastran profile this 'contact surface' is not available under the BC>create> menu. Is there document giving an example on this pre-process issue. Thanks!
Hello All, I am tring to utilize Virtual Fluid Mass method in order to calculate natural frequencies of fuel tank. However, aacording to results, dry modes are consistent with measured acceleration data, but, wet modes are completely different than test data. Three wet modes, three dry modes are calculated, but wet mode shapes are completely same. Just natural frequency values are different. According to test data, mode shapes of first three mode are completely different. Do you have any idea to sole this problem? Pictures shown below explains my step card. **ELIST 666 is created, because both sides of baffle plates inside of the fuel tank contact with fluid. **ELIST 555 is created, beacuse inner side of the fuel tank contact with fluid. **During shaker tests water is used in order to represent fuel in the tank. Hence, density of water is considered in MFLUID command.
Hello, I have an enclosed volume with a fluid inside. And I have to apply an Acceleration PSD to it. So: 1) I am using MFLUID with VMOPT 2 in order to obtain a good modal base for my analysis. 2) To simulate the pressure, I am using a PLOAD4. I've made several tests for this Analysis to work, but my RMS Von Mises is incredibly high. I tested: 1) Normal Modes of the Structure with and without MFLUID: all is OK and I can see a reduction of the Frequency. 2) Modal Frequency Response without MFLUID is OK: the RMS values are pretty low - around 4-6 MPa. 3) BUT the Modal Frequency Response with MFLUID gives me HUGE RMS values. 4) I checked the Eigenvector Values of the Normal Modes Analysis - with and without MFLUID. The analysis with MFLUID has numbers around 1000 times higher. Question: is there some way of obtaining a good Modal Base for a Modal Response Analysis, by using the MFLUID card?