batch_mesh_cfd.pdf

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Tutorial
CFD BATCH MESH
PUMP
Table of Contents
1. Introduction ...................................................................................................................................2
1.1. Prerequisites .........................................................................................................................2
1.2. Case description ...................................................................................................................2
1.3. Data files ...............................................................................................................................2
2. Create the Surface Meshing Scenario ..........................................................................................3
3. Create the Boundary Layers Scenario ........................................................................................12
4. Create the Volume Meshing Scenario ........................................................................................21
5. Running the Batch Meshing process ..........................................................................................28
6. Re-applying the Batch Meshing process on modified geometry .................................................31
7. Run the Batch Meshing using ANSA scripting language ............................................................34
7.1. Running from launcher........................................................................................................34
7.2. Running from Command Prompt ........................................................................................35
7.3. Run Description...................................................................................................................36
7.4. Background execution.........................................................................................................36
8. Conclusion ..................................................................................................................................37
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CFD Batch Mesh – Pump
1. Introduction
This tutorial will highlight the automation that can be achieved in the surface and volume meshing
procedure with the use of the ANSA Batch Mesh tool in CFD applications. The Batch Mesh tool is a
highly flexible tool that offers many different possibilities in the field of CFD meshing and model
preparation. Moreover, this fully automated process can be reapplied on other geometries, provided
that they have been modeled using the same property names.
The steps described in this tutorial are:
- Read the ANSA file containing the geometry,
- Create the Batch Mesh Scenarios for surface meshing, boundary layers generation and volume
meshing,
- Create advanced filters to select and add the regions of the model in the scenarios,
- Set the parameters and quality criteria for each meshing scenario,
- Execute the Batch Meshing,
- Use the ANSA scripting for further automating the Batch Meshing procedure and
- perform the model meshing in batch mode.
1.1. Prerequisites
This tutorial requires that the user is familiar with the basic ANSA interface and terminology.
However, it is suggested that the user first goes through the tutorial “External Aerodynamics” in
order to familiarize himself with the ANSA functionality and terminology used here. Finally, it is
suggested that, while working on this tutorial as well as other CFD models, the CFD ANSA GUI and
the CFD ANSA defaults are used.
In order to use the CFD GUI, start ANSA and select the CFD option from the pop-up launcher. The
CFD GUI contains the most important ANSA features used in CFD models.
1.2. Case description
First, the surface of the pump should be meshed using various mesh parameters. Then, boundary
layers will be grown on the inner surface of the geometry from two separate regions, using different
parameters for each region. Finally, the rest interior volume will be meshed using tetrahedral
elements.
1.3. Data files
The file required for this tutorial is the “batch_mesh_cfd.ansa”. This file can be found in the
following directory:
/.../ansa_v13.x.x/tutorials_and_examples/tutorials/CFD/cfd_batch/tutorial
_files/
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CFD Batch Mesh – Pump
2. Create the Surface Meshing Scenario
Start ANSA and from the pop-up launcher
select the CFD option so that ANSA starts with
the CFD layout.
Tip!: In Linux 64-bit, run the “ansa64.sh” file.
In Linux 32-bit, run the “ansa.sh” file.
In Windows 64-bit, run the ansa64.bat file.
In Windows 32-bit, run the ansa.bat file.
Please refer to the “ CFD Project Practices.pdf”
document for a description of the CFD layout.
Select FILE>OPEN to read the ANSA file. The
File Manager window appears. Navigate and
select the file “ batch_mesh_cfd.ansa ”.
Press “ OK ”.
This file contains the geometry of the model.
Switch to MESH menu.
Activate the SHADOW flag
and switch to PID view
mode.
PID
ENT …
PID …
MID …
PID …
SHADOW
Open the Property List window to view
how the parts are arranged in
properties. The model is water tight and
contains eight different regions. Each of these
regions corresponds to a different PID and it
will be meshed with different parameters.
The Property List will be used as a manager,
assisting with the organization of the different
regions of the model.
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CFD Batch Mesh – Pump
Open the Batch Mesh Manager (its
icon is located near the PIDs icon). In
this window, you will create three
different scenarios.
The first scenario will include the surface
meshing of the model.
The second will create the boundary layers
and, finally, the third will mesh the remaining
interior model volume.
The order mentioned above is important. First,
the surface mesh should be complete in order
to generate the layers and finally to mesh the
remaining volume.
In the Batch Mesh
Manager , add one
surface meshing
scenario by selecting
the “ Meshing
Scenario ” entry in the
New ” button.
New
Meshing Scenario
Wrap Scenario
Layers Scenario
Volume Scenario
Note: Every time you create a scenario, there is also added a Default_Session . This session is
generated automatically by ANSA and the user cannot delete it. In this session, there are loaded
automatically the parts which are not loaded in any other session of the same scenario. If you need
only one session, you can use directly the Default_Session. If you do not want to use the same
settings for all available PIDs, then you can create as many sessions as you want.
Select with the left mouse button the
Meshing_Scenario_1 ”, click on the “ New
button and select the “ Session ” entry.
Tip!: Alternatively, use the drop down list
appeared if you right-click on the
“Meshing_Scenario_1”.
Repeat the same
action two more times
to create in total three
new sessions.
(The default session will not be used).
New
Scenario
Session
Finally, you should end up with one scenario
for the surface mesh containing three user-
created sessions and the Default_Session .
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CFD Batch Mesh – Pump
In the “Meshing_Scenario_1”, click with the
left mouse button on “ Session_4 ” and click
once more or press F2 to enter the edit mode
and rename it .
Give this session the name “ edges ” and press
ENTER to confirm the change.
Using the down arrow key go to “ Session_3 ”,
press F2 to rename it to impeller ”. Do the
same for “ Session_2 ” and rename it to
volute ”.
The sessions order in the meshing scenario
will allow the progressive surface meshing
from the areas with small element length to
the areas with a larger element length. This is
a general practice that should be followed in all
Stages of the Batch Meshing.
After defining the names of the three different sessions, the next step is to define which regions are
going to be used in this scenario and how they are going to be allocated in the three created
sessions.
Here, the different regions of the model have already been assigned to different properties, so that
they can be handled easier.
In general, there are two different ways to allocate regions to sessions; either manually or with the
use of filters. In this tutorial, filters will be used because the same filter can be later re-applied in
alternative geometries, provided that the property names remain the same in the alternative
geometries.
Even the same Batch Mesh setup can be applied to a totally different geometry, if the property
names remain the same.
In order to define the contents of a scenario,
right-click on the scenario (here
Meshing_Scenario_1 ”) and select
Edit”->“Contents ”.
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