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CFD stands for Computational Fluid Dynamics - the branch of mechanical engineering dealing with Fluid Flow and Heat Transfer. Whether you are a fresh graduate with engineering degree or a seasonsed professional with industry and design background, you will find plenty of technical stuffs on CFD analyses and CFD software (both commercial such as FLUENT, CFX and COMSOL as well as open-source Gmsh, OpenFOAM and ParaView. However, one must note that the term CFD is also used in commodity trading where it stands for Contracts for Difference.
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Y-plus: Estimation of first layer height near wall
Estimate height of the 1st layer height of the mesh as per recommended y+ value of the chosen solver, a better guess than choosing an arbitrary value.
Here is Excel version: Y-Plus and Boundary Layer Height Estimation using Excel. The default values have been specified to avoid arithmetic errors. Please ensure you specify all the values as per the operating conditions chosen in simulation. The default value of y+ is set = 30, appropriate for most high-Re turbulence models. In case a low-Re turbulence model such as SST is being used, change this value to 1 or maximum 5.
In order to demonstrate the effect of the cell-based and vertex-based scheme, simulations were performed using same mesh, material properties, solver and boundary conditions. The area-averaged value of Y-plus matched the observations described above. The mesh used is shown below.
The contour plots for the Y-plus are shown below. Based on the flow conditions and material properties, following are derived parameters:
The calculation was repeated in CFX using velocity profile specified by exponential function V0*[1-(r/R)7] keeping all other parameters constant. The reported value of Y-plus has reduced from 33.2 to 24.2
The content on CFDyna.com is being constantly refined and improvised with on-the-job experience, testing, and training. Examples might be simplified to improve insight into the physics and basic understanding. Linked pages, articles, references, and examples are constantly reviewed to reduce errors, but we cannot warrant full correctness of all content.
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