**frontal surface area**is the projected area, along the path of the fluid, to a plane perpendicular to the direction of motion. it is the area that presents the object to the fluid path. We call this area the "Midship" of the ship. The higher this area is, the greater the drag force is.

Naval architects use the value "Midship section coefficient" (Cm) to express the slenderness of the ship's hull form . This coefficient equals 1 only for a cuboid, for slender ships this coefficient always less than 1..

Remark: For the calculation of the profiled bodies tested in the wind tunnel , the values of Cz and Cx are given according to the wing surface.

The Reynolds number is also calculated differently if the body is shaped, or if the body is a flat plate or any geometric object.For more details see this page on the Reynolds number

**The value of the waterplane area**

*waterplane area:***AWL**, is used to obtain the coefficient of surface waterline

**Cwl**= Awl/ (L*B) . This coefficient is equal to 1 only for a cuboid, for slender ships, this coefficient is always less than 1. Using the midship or

**frontal surface area**in

**standard: Sample calculation of aerodynamic drag or resistance of a vehicle based on its frontal area and CD. The Cx and midship objects or vehicles proposed in mecaflux are modifiable, if you prefer to enter your own data to calculate the Drag force**

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