Immersed Body Valve Simulation using Ansys CFD: Part 1
Presenter: Mingyau from Ozen Engineering
In this video, I'll be demonstrating how to set up a CFD analysis in CFX using the immersed boundary method. We'll start with a SOLIDWORKS assembly to extract the flow region. The benefit of the immersed boundary method is its ability to quickly and easily perform rigid body or motion analysis of components. However, the trade-off is reduced accuracy and boundary resolution compared to a well-defined model.
Project Overview
This is our OZEN EDITORIAL PROJECT. We'll be using the same plug valve flow region as in previous projects. Let's proceed with the setup:
Steps to Set Up the Analysis
- Go to Workbench > Prepare > Volume Extraction.
- Select the capping surfaces and the internal surface, then hit OK to generate the model.
- Remove unnecessary edges by filling and deleting them to simplify the model.
- Turn on the plug for overlapping sections and suppress unnecessary parts for physics.
- Decide between a full model or a half-symmetry model for easier handling.
- Perform a split body operation to finalize the model for analysis.
CFX Method Setup
Attach a CFX method to the model. The immersed body model is the easiest to set up, and that's what we'll use today.
Mesh Setup
- Set up the global coordinate system.
- Define the sphere size (e.g., 20 mm) and refine the mesh size (e.g., 1.5 mm) for accuracy.
- Update the mesh to achieve approximately 62,000 nodes.
Simulation Setup
- Open CFX.pre to set up the simulation.
- Create a new domain for the valve as an immersed solid.
- Set the fluid to water and define symmetry, inlet, and outlet conditions.
- Adjust the mesh by adding an inflation layer for better boundary resolution.
- Update the mesh and set 500 time steps for convergence.
- Run the simulation on 4 cores.
Results and Analysis
Upon reaching convergence criteria, examine the results:
- Turn on symmetry and the valve to plot pressure and velocity.
- Calculate the mass flow averaged total pressure at the inlet, which is 2.69 psi.
This concludes the basic steady-state simulation setup. Further analysis can be performed as needed.
Immersed Body Valve Simulation using Ansys CFD: Part 1 Hi everyone, this is Mingyau from Ozen Engineering. In this video, I'll be demonstrating how to set up a CFD analysis in CFX using the immersed boundary method.
We'll start with the SOLIDWORKS assembly here and use it to extract the flow region. The benefit of the immersed boundary method is that it allows us to perform rigid body or motion of components inside of an analysis quickly and easily.
The trade-off is that it's not as accurate, and we don't get as much boundary resolution or flow profile as we'd like with a well-defined model. This is our Ozen Editorial Project. In this video, I'll be showing you how to perform an immersed body valve simulation using Ansys CFD.
The flow region is the same plug valve we've done previously. I'll extract the flow by going to Workbench, Prepare, Volume Extraction, selecting the capping surfaces, and selecting the surface on the inside. I'll hit OK, and it generates this model.
Because this is a flow analysis, and it's an immersed boundary analysis, we don't need the flow area that the valve is extracted from. I'll select a set of faces, remove the hole, fill and delete unnecessary edges to make the matching easier, and turn on the plug.
The rest we don't need, so I'll suppress for physics. We can do a full model or a symmetry half-symmetry model, which is easier to work with. I'll go ahead and do a split body of all of these. That's the model we'll use for our analysis, a half-symmetry model.
Back in Workbench, I'll attach a CFX method to this. I have several other options for moving mesh and mesh adaptation, but the immersed body model is the easiest one to set up. That's what we'll play with today.
I'll build up a mesh of influence and set up the global coordinate system, where I want the sphere to be, roughly. I want a small mesh inside of this, so I'll remesh it. A 2.5-millimeter mesh seems appropriate. The smaller the mesh, the more accurate this method will be.
I'll open up CFX.pre for setting up the simulation. I'll create a new domain here, insert the valve (our part), and make it an immersed solid. I'll do a stationary one, which I can move up and down later as needed. The benefit of the immersed solid is that it's very tolerant to topology change.
I'll switch this to water and add a symmetry, inlet, and outlet. I'll do an inlet here, with one meter per second, and assign a boundary for the outlet. I'll specify the average relative static pressure of zero.
Looking at this mesh, I probably should have made it a little more refined at least in the boundaries. I'll go back here and put in an inflation layer, so I can get smaller elements right along the boundary.
I'll increase this to 500 time steps for convergence, run the simulation, and go to the solve step. I'll run this on 4 cores. We've reached convergence criteria. I'll turn on the symmetry, the valve, and plot, for example, the pressure. I'll plot the velocity and grab the outlet.
I want the mass flow averaged at the inlet, and I want the total pressure. I'll show you why this is important. 2.69 psi. This is a basic steady-state simulation, and if I just wanted to do a steady-state simulation, that would be the end of it.
