![]() For an example of this technique, please see Submodeling Analysis of a Shaft 4) Use assembly meshingĭepending upon the physics which you are using you may be able to use assembly meshing. Submodeling is the process of solving a sequence of models with different levels of details and different meshes. For an example of this technique, please see Virtual Operation on a Wheel Rim Geometry 3) Use submodeling Please read Using Virtual Operations to Simplify Your Geometry for more details. They can be useful on any geometry to quickly ignore details which are not critical to the analysis. Virtual operations are used to approximate the geometry for the purposes of meshing. Please read Working with Imported CAD Designs for more details. If you are working with CAD data coming from another source, use the Defeaturing and Repair operations to remove any small faces not critical for analysis. Reduce the geometric complexityĬarefully check your geometry to see if it contains any features that you do not actually need for your analysis. Most physics interfaces include boundary conditions which can be used to represent thin structures, thereby avoiding modeling, and meshing, of thin domains. Often, a thin-walled structure or a small gap does not need to be explicitly modeled. Similarly, if a 3D geometry is uniform (or nearly so) around an axis of revolution, consider reducing it down to a 2D axisymmetric model. For example, if a 3D geometry has uniform cross-section in one direction, consider reducing it down to a 2D model. If your geometry has any symmetry (or near symmetry) and you expect your solution to also be symmetric (or nearly symmetric) consider if you can reduce your problem size. Several different techniques can be used here, investigate some or all of these suggestions. See Knowledge Base solution 866 for hardware recommendations. If you anticipate running many models of similar size, then it is reasonable to consider a hardware upgrade. If you are using a Floating Network License you can also solve on a cluster. See if you have access to a machine with the needed amount of memory. Once you know how much memory is installed in your system and have a rough idea of how much memory your model will take you can consider one of several possible approaches. Knowing the size of the models that you want to solve is important. ![]() Fit a second order polynomial curve to this data to roughly predict how much memory you will need for the actual problem that you want to solve. Monitor the memory requirements and DOFs for these smaller models. Start by solving smaller models with the same physics, or use a coarser mesh to solve the same model. 3) Predict your memory requirements by solving smaller models The number of DOFs is related to the amount of memory a particular model will need. Knowledge Base 875 describes how to approximately predict the number of degrees of freedom based upon the mesh. This will be reported in the Messages window within the COMSOL GUI when you start to solve the problem. Next, check the number of degrees of freedom (DOFs) in your model. COMSOL requests memory from the operating system and will always use both the physical RAM and virtual memory available on your system. However, using virtual memory is slower than storing data in RAM, therefore the virtual memory will not, by default, be much greater than the installed RAM memory. Most operating systems will also be using the hard drive (virtual memory) to store data. The reason for out of memory error messages is that COMSOL is requesting more memory from the operating system than is available on your computer. Before resolving this issue, you should go through the following steps: 1) Check the amount of available memory on your systemįirst, check how much installed memory (RAM) is in your computer.
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