Question 3.13: Analyze the fluid flow around an example racecar model shown...

The SolidWorks FlowSimulation is used to simulate the airflowaround the rackcar body. The flow Simulation tool is included in the add-ins of the SolidWorks. It can be activated by selecting the tool in the list of add-ins under Options→Add-ins as shown in Fig. 3.62. The SolidWorks Flow Simulation provides the project wizard to guide users in defining a flow simulation model by following the main steps shown in Fig. 3.63. Firstly, the CAD model is imported, the configuration of interest is specified, and the name of flow simulation is created. Secondly, the preferable units are specified for all of parameters and variables used in the simulation model. Thirdly, the analysis type is given; the flow simulation can be for an internal or external flow; moreover, it is optional to include (1) cavities or internal surfaces, (2) heat transfer and radiation, and (3) historical data over time. An external simulation with excluded cavities is defined in this example. Fourthly, the types and properties of fluid are defined; the software include a design library that have many commonly used fluids and gases. Fifthly, the wall conditions are defined for fluid–solid contact surfaces. Sixthly, initial conditions of fluid are defined; the relative speed (i.e., 90 m/s) of the airflow and racecar is defined along the x-axis for this example.

A flow simulation model involves in a large number of state variables, and it is unnecessary to include all of derived variables in the solving process. Figure 3.64a shows the interface where the variables of interest can be specified as the analysis goals. In addition, the computational volume can be should be adjusted with the consideration of computation time and accuracy (see Fig. 3.64b); users can also specify the levels or sizes of meshes or apply control meshes in the areas of interest when they are needed.
Figure 3.65 gives the statistic data of solid and fluid meshes and the solving process. Figure 3.66 shows the example plots of velocity and pressure distribution over a selected cutting plane. The goals of the flow simulation is shown in Table 3.14. It is found that the drag force along moving direction (x-axis) is 4802 (N).

Table 3.14 The results of analysis goals in flow simulatioon