The Computational Fluid Dynamics solution contains the flow variables, or velocities and pressure of the airflow, at each point in the mesh. Conservation of mass and momentum equations are used to obtain these values of the flow variables. Each control volume is analyzed for the mass that flows into it and out of it, which creates a balanced equation. The flow variables along an edge of a control volume are averaged between the values of the mesh points on the endpoints of the edge.
The CFD program FLUENT calculates the airflow around an aerofoil. Fluent convergence histories graphs and calculated streamlines for different incidence angles of the airflow are compared to experimental findings from a wind tunnel. In our CFD lecture, the pressure coefficient on the aerofoil surface is also compared between the calculated and measured findings for an incidence angle of 17 and 15 degrees. . Pressure fields and calculated streamlines were made for incidence angles of 10 and 17 degrees.
The lift-to-drag ratio varies with incidence, and this affects when the aerofoil stalls. There are many more streamlines for an angle of incidence of 17 degrees compared to the 10-degree case, and the aerofoil for 17 degrees incidence is stalled. The angle of incidence is also called the angle of attack that the wing makes. the lift force is perpendicular to the wing. The lift force is then directed both up and to the back. The backward component of this lift is called drag. A higher angle of incidence creates greater drag. so that the lift-to-drag ratio decreases as the angle of incidence increases.
Examples of turbulence were then considered: these examples include tornado funnels. water vapor vortices from aircraft. a broken bridge due to a vortex system at the base. and thermal convection on a heated plate. This turbulence can be characterized by the Reynolds number, which is low for smooth laminar flow and high for turbulent flow. The regions of laminar and turbulent boundary layer flows were examined, as well as the transition boundary layer between them. The definition of turbulence and some of its effects were considered. .