The surface pressure coefficient () is a dimensionless quantity used in fluid dynamics, especially in aerodynamics, to describe the pressure distribution over a body’s surface exposed to a fluid flow. It is commonly used to analyze and understand the aerodynamic forces acting on objects such as airfoils, wings, and other streamlined or bluff bodies.
This equation shows the variation of the surface pressure coefficient around the circular cylinder as a function of the polar angle (). The pressure coefficient is highest (maximum pressure) at the top and bottom of the cylinder ( or ), where , and it reaches its minimum (minimum pressure or maximum suction) at the sides of the cylinder (), where .