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# SOLIDWORKS SIMULATION TECH TIP: Transferring Flow Loads to Shell Elements

In SOLIDWORKS, we have the ability to take advantage of an integrated interface where we can use multiple simulation tools. If you are using Flow Simulation and Simulation (FEA), you can export Flow Simulation loads to FEA studies. In the following example, I ran flow over a truck body and exported the pressure loads to SOLIDWORKS Simulation. The goal of this particular problem is to identify the displacement of a truck cap as a function of the aerodynamic pressures.

In this example, there is 90mph airflow over the truck body. To start this problem, I ran through the Flow Simulation Wizard tool and set the problem as an external flow analysis. I gave the moving fluid (air) an initial velocity of 90 mph normal to the truck body and ran the study. If I want to see how aerodynamic my model is, I can view flow trajectories over my model. Figure 1 shows a cut plot of the velocities over the body with flow trajectories modeled as streamlines.

Figure 1: Velocity Cut Plot with Streamlines
Due to pressure being derived as an output variable in Flow Simulation, I can export that information over to a Finite Element Analysis in SOLIDWORKS Simulation. If you are using SOLIDWORKS 2015, you do this by going to the toolbar: Tools > Flow Simulation > Tools > Export Results to Simulation. Once in Simulation, I need to import the flow loads into my study. I do this by going to Study Properties > Flow/Thermal Effects > Fluid Pressure Option > Include fluid pressure effects from SOLIDWORKS Flow Simulation (Browse to .fld file).

When this operation is completed, SOLIDWORKS Simulation will map the flow results over the mesh. It is CRITICAL that you mesh prior to importing the flow results. This is because Flow needs to identify the pressure loads at the node locations on the mesh. For the truck cap analysis, I used Shell Elements in SOLIDWORKS Simulation by right-clicking on the body and selecting “Define Shells by Selected Faces.” After the shell has been defined, I can import my pressures, and run the study. Figure 2 shows the displacement plot as a function of the pressure loads in Flow.
Figure 2: Displacement Due to Aerodynamic Pressure

Like this example, one main application where the combination of these tools is handy is flow over a body to identify lift. Lift is a force that acts on the body perpendicular to the direction of the airflow and is in contrast with drag. In this example, I was able to successfully run a fluid simulation over the truck and import those pressure gradients into Finite Element Analysis. The FEA gave me the displacements of the model as a function of the lift force on the model, as shown in Figure 2.

Being able to work with a diverse toolset in SOLIDWORKS gives me the ability to analyze multiple conditions in one single interface. If my model isn’t as aerodynamic or as stiff as it needs to be, I have the ability in SOLIDWORKS to run analytical studies concurrent to my design process. If I were to use a third party program, I would be constantly importing and exporting between the software packages to ensure an optimum design. In SOLIDWORKS, I can do all of this in one easy interface.

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