Axi-symmetric nozzle
Introduction
- This is an example of mesh generation for an axisymmetric nozzle analysis.
- Geometry from the following paper used in FDA's Nozzle Challenge, a benchmark test program for simulation validation of non-Newtonian fluids hosted by the U.S. Food and Drug Administration.
Trias, Miquel, Antonio Arbona, Joan Massó, Borja Miñano, and Carles Bona. “FDA’s nozzle numerical simulation challenge: non-Newtonian fluid effects and blood damage.” PloS one 9, no. 3 (2014): e92638.
Geometry
Use given fda-nozzle-scaled.stl file as geometry. This file is a three-dimensional geometry with axisymmetric faces in the x-y plane extruded in the z direction. BaramMesh does not directly create an axisymmetric mesh, but rather creates a three-dimensional mesh, rotates one of its faces (extrudes), and exports it as an axisymmetric lattice.
Click the [Import] button at the bottom to select the stl file.
Turn on the [Split Surface] option to separate boundary surfaces and pressing the OK button, a window like the one on the right in the image below will appear. You can see that eight boundary surfaces are created. Click the OK button to load the geometry.
When you read the stl files, you'll see eight faces numbered like zone0_surface, zone0_surface1, .... We'll rename them to distinguish them.
In Geometry, select surfaces and right-click and select Edit/View. In the window that opens, change the name as follows
- zone0_surface : back
- zone0_surface1 : front
- zone0_surface2 : bottom
- zone0_surface3 : wall
- zone0_surface4 : wall1
- zone0_surface5 : out
- zone0_surface6 : in
- zone0_surface7 : wall2
Click the [Next] button to move on to the next step.
Region
Click the (+) icon at the top to create a region. Move the mouse to the intersection of the lines that appear in light green color in the graphics window and position it inside the computation domain. Click the [Add] button to complete the setup.
Click the [Next] button to move on to the next step.
Base Grid
Set the number of grids to 600, 50, and 2. Click the [Generate] button to generate the base grid.
Click the [Next] button to move on to the next step.
Castellation
Use the default settings.Click the [Refine] button and the castellation step starts.
The result looks like this
Click the [Next] button to move on to the next step.
Snap
Use the default settings and click the [Snap] button to start snap.
Click the [Next] button to move on to the next step.
Boundary Layer
Click the (+) icon under [Configuration] to add a [Setting], and set it as follows
- Number of Layers : 5
- Thickness Model Specification : First and Expansion
- Size Specification : Relative
- First Layer Thickness : 0.15
- Expansion Ratio : 1.2
- Min. Total Thickness : 0.3
- Boundary : wall, wall1, wall2
Use default values for [Advanced] Configuration.
Click [Apply] button to start boundary layer step.
The final mesh looks like this
Click the [Next] button to move on to the next step.
Export
To export to an axisymmetric mesh, click the [Axi-Symmetry] button under [2D Exports] to open the following window.
Select path and enter folder name. And set values as follows + Source Boundary : back + Exposed Boundary : front + Angle : 5 + Axis Origin : (0 0 0) + Direction : (-1 0 0)
Pressing the OK button will create a folder that BaramFlow can read.
Exported mesh looks like the image below
