Week 3 - External flow simulation over an Ahmed body.

 Ahmed Body: It is a first generic car model generated to study the flow separation over the bluff bodies to analyze the flow patterns and forces acting on the moving body in the fluid region. It is considered to be a general model representing car/body moving in the open environment. This analysis helps us to study the flow characteristics in various design models of vehicles, aircrafts, ships etc. translating in the fluidic medium. From these flow patterns one can perdict the various forces such as lift and drag acting on the body due to fluid deflections. These drag and lift  forces are important parameters to be analyzed prior to finalize the vehicle design and power require to translate it in this medium. 

Wake region: This is a region created due to the flow separation that takes place due to the geometry of the bluff body. The flow in this region get converted to eddies/swirls of fluid and the varition in pressure is observed. The negative pressure in this region is generated due to the high velocity eddies formation and limited access to fluid flow pattern due to restricted fluid movement in this region. The wake region plays a key role in drag calculations for vehicle design considerations and it can be reduced with geometrical alterations to save power losses.

Point of Separation: It is the point from where the flow pattern deflected or separated its contact with the bluff body. As the body translates opposite to the flow direction, the abrupt changes in geometry or shape edges on the front portion of body facing fluid flow is the separation point.The flow profile before and after the separation point are different which generates the different forces to act on the body. The magnitude of drag and lift forces also depends on this point, so to reduce the drag forces on the moving body the flow separation can be prevented using  fillets or design modifications.