Coarse mesh is an application of element-based structural analysis and is closely related to finite element analysis (FEA), computational fluid dynamics (CFD), and similar simulations. It concerns a kind of grid or mesh with relatively large CE and can divide a domain in the mathematical modeling. In other words, if a space or structure is divided into larger number of smaller segments for simulation or computation this is known as coarse meshing. Coarse meshes are normally utilized for preliminary analyses, low order models, or whenever computational cost is a critical factor than the accuracy.
This blog will focus on the definition of coarse mesh, the procedure of implementing this method and cases where this method is most suitable. Also, we will focus on the difference between coarse mesh and fine mesh in terms of usage, and clear out all the confusion.
What Does Mesh Mean in Numerical Simulation?
Mesh in FEA, CFD, and such other methods, is described as the subdivision of a continuous object or domain into elements or cells. Each item stands for a material facet of the model and lends itself conveniently to the mathematical analysis of application of mathematical equations to problems involving stress distribution, fluid flow, heat transfer and electromagnetic fields.
The size of these elements defines the character of a mesh as coarse or fine. A fine mesh sub divided into its element and contains a larger number of elements than a coarse one since the later has fewer elements hence giving the analysts a more detailed picture. A coarse mesh on the other hand, consists of larger elements and fewer numbers of the same; as a result computations are faster, but the results obtained are less refined.
Coarse mesh characteristics
Large Elements: The grid or cells in the coarse meshing is bigger than the grid or cells in fine meshing which means that few elements are needed to accommodate the large domain.
Lower Computational Cost: Consequently, the number of approximating elements are small and this decreases the necessary computational power needed for obtaining the simulations’ solutions.
Reduced Accuracy: Ending up in a big difference from the analytical solution, coarse meshes give less accurate information as the fine meshes provide.
Simpler Models: This is usually applied to simple geometries, or when one is interested in a first estimate of the results, before ‘converging’ to more refined meshes.
When to Use Coarse Mesh
Approximation by coarser meshes is used in cases when it is sufficient to determine the global picture rather than details. Below are some common use cases for coarse mesh:
Initial Simulations or Prototyping: When designing simulation processes, engineers make raw grids when making preliminary analyses of the behavior of a particular system to use a detailed grid that consumes more time for analysis later.
Simple or Symmetric Problems: Depending upon the geometrical complexity or the nature of the problem under investigation, a simple grid of large elements may be adequate to give some measure of quantitative appreciation.
Large Domain Analysis: There are however situations where the domain is very large and the use of the fine mesh may prove to be expensive. A coarse mesh makes an analysis for the large area inexpensive and effective.
Conceptual Studies: In cases that a general description of the performance is enough, stress patterns, particularly in early design stages, can easily be done using the coarse mesh in the simulation.
Coarse mesh may also be used as a precursor of a fine mesh simulation. Fine mesh is created on the basis of a coarse mesh formed initially for the simulation. It is for this reason that engineers and researchers may first run simulations using gross meshing to determine areas that would need dense meshing. Finally, where they had located these areas, they move cliqued fine meshes to increase precision in areas that require high accuracy.
Advantages and Disadvantages of Coarse Mesh
Benefits
Faster Computation: Small number of inserted parts suggests that one can complete the simulation in a relatively shorter interval of time, which makes them suitable for providing a quick analysis.
Resource Efficiency: Coarse mesh is more memory and computationally efficient, such that large models or constrained computing resources can be used.
Good for Preliminary Testing: It is useful in making predictions concerning areas likely to be challenging should the project proceed quickly, yet is not too costly.
Drawbacks
Lower Accuracy: The numerical results of coarse mesh may be inaccurate for fine details of complex systems and fails to provide details required for detailed analysis.
Risk of Missing Critical Details: It indicates that aspects of small scale could be missed out, which in turn distorts the outcome.
Need for Refinement: However, in most of the cases, the use of coarse mesh does not provide adequate answers and requires additional fine mesh simulation for comprehensive solutions.
How to Optimize Mesh Size
While using the cad geometry, the right resolution of the grates in order to simulate the flow field is critical. Some ways to optimize mesh size include:
Adaptive Meshing: Incorporation of software tools that autonomously adjust the mesh density and make it fine in areas of high stress and comparatively lower density in other areas.
Hybrid Meshing: This means that the two meshes with a course and a fine network structure in the same model gives a good balance of speed and accuracy.
Mesh Convergence Study: A mesh convergence study is also to be done to observe the effect of mesh size in the calculations and to decide the suitable mesh size for the calculations to be both accurate and efficient.
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Conclusion
The problem with coarse mesh is that they are viable in performing preliminary analysis in terms of time and computation effort. Though it cannot give as accurate a result as with fine mesh, it lets the engineers/researchers determine trends and issues that are worthy of a refined simulation before investing time into it. This brings up basic knowledge of when and how to apply coarse mesh in the project, together with time-saving strategies, concerning pacing and computation capabilities.
By considering the first grid to be coarse and adding new grids if necessary, the professionals can tune the simulation, getting the most accurate solution within the short computation time.