Fortunately, SOLIDWORKS Flow Simulation provides an easy way to avoid this all we must do is tell the software that our ground is moving at the same speed as the air. This will create an unwanted boundary layer at this interface which could potentially affect the results. However, if we are not careful with our set-up, and we do nothing more, we will have created relative motion between the air and the ground. This creates the correct relative motion and boundary layer between air and vehicle. In a typical external flow simulation project, we will fix the vehicle in place and then move the air relative to the vehicle using an inlet velocity boundary condition. In flow vernacular, there is no boundary layer at the interface of the air and the road. There is relative motion between the vehicle and the road and between the vehicle and the air, but (assuming a windless day) there is no relative motion between the air and the road. In real life, a vehicle moves down a road and creates drag. Luckily, SOLIDWORKS Flow Simulation makes the set-up easy.
Fortunately, CFD has largely replaced this expensive process, but care is required to ensure accurate replication of the physics of vehicle flow. This is a very costly exercise wind tunnel time is very expensive, as are the costs associated with constructing the scale models and hiring technicians to run the tests and crunch the numbers. They would build scale models of candidate shapes and measure the drag of these candidates in the wind tunnel. In part 2, I am going to demonstrate some of the nuances for correctly setting up a “Virtual Wind Tunnel” in SOLIDWORKS Flow Simulation.īefore the widespread adoption of Computational Fluid Dynamics (CFD), engineers who sought to explore the aerodynamics of different vehicle shapes would typically book testing time at a wind tunnel facility. In part 1 of this Blog article I investigated the drag characteristics of the Tesla Cybertruck and explored how symmetry boundary conditions can be used to speed up a flow analysis project in SOLIDWORKS Flow Simulation.