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Home / How to Set Analysis Condition / Fluid Analysis [Bernoulli] / Layer Mesh Setting
Layer Mesh Setting
Layer mesh is set up.
It is known that for the fluid analysis, the higher accuracy is obtained by creating multilayer meshes along the wall surface (solid wall, slip wall boundary condition, and boundary with solid material).
Please see Meshing Setup near the Wall Face for more detail.
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Notes |
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Specifying Method |
Automatic: Creates the layer meshes of the wall face automatically from the flow velocity, the material property, the laminar flow/turbulent flow settings, and the the shape of the inlet. Setting can be enabled only when the dialog box is opened by the Fluid Analysis tab. Specify mesh height of 1st layer: Specifies the mesh height of 1st layer (h1), growth rate (r), and the number of layers (n). The growth rate is the ratio of mesh height of the ith-layer mesh (hi) and i+1st-layer mesh (hi+1).
Specify total mesh height: Specifies total mesh height (yn), growth rate (r), and the number of layers (n). The growth rate is the ratio of mesh height of the ith-layer mesh (hi) and i+1st-layer mesh (hi+1).
By pressing [Confirm] button, the height of mesh (hi) of each layer and the height from the wall face (yi) can be confirmed.
The mesh height (h) and the mesh height from the wall face (y) are shown below.
See [Meshing Setup near the Wall Face] for more information.
Do not create layer meshes: Does not create layer meshes. |
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Parameters for Automatic Creation |
If [Create layer meshes automatically] is selected, several parameters are used to
If the forced inflow/outflow is selected, the layer mesh height is automatically set so that the dimensionless height y+ of the 1st layer of the wall face is 100 or close to it. See Meshing Setup near the Wall Face for the dimensionless height y+. By selecting [Specify target y+], the target value of y+ can be changed from the default value of 100.
If the forced inflow/outflow is not set in the analysis that takes into account the buoyancy , [Expected Temperature Difference] must be set to determine the layer mesh height.
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Height Automatic Adjustment Method |
If the domain is smaller than the specified height, the layer meshes may not be created with specified height. If [Adjust to a uniform height] is selected and automatic adjustment is necessary, the height is adjusted to the thinnest area as a uniform height. Examples are shown below. The height is adjusted so as to create the layer mesh in the narrow area in the center.
If [Adjust for specific nodes (coefficient automatically specified)] is selected, set the height lower at the area requiring automatic adjustment and gradually increase it farther away from that area. Examples are shown below. The mesh is set at a height greater than the width of the narrow area in the center. However, the high mesh is not allowed in the narrow area. The height is adjusted so as to create the layer mesh in the narrow area in the center. The height is higher as farther from the narrow area in the center. This method prevents the overall layer meshes from having a lower height, even having areas where a lower height is required locally.
The adjustment factor is defined as the ratio of the height of one node to that of the next node. It is automatically selected between 1.0 and 1.1 to create layer meshes. The selected adjustment factor is displayed in the output window.
If [Adjust for specific nodes (coefficient manually specified)] is selected, set the height lower at the area requiring automatic adjustment and gradually increase it farther away from that area. The adjustment factor, which indicates the height increase ratio, can be specified.
As an example, create layer meshes with an adjustment factor of 1.5. Due to a drastic increase in the height of layer meshes, it is observed that the height reaches the specified height in about four meshes
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