Answer:
For calculating the total force on a surface must integrate the fluid shear stress over the whole surface.
Step-by-step explanation:
By definition, the total force from the fluid in the cartesian system of coordinates is defined as:
![F=\int\ {\tau (x,y)} \, dx dy](https://img.qammunity.org/2020/formulas/engineering/college/84xukt6vibiwnkbjfqes8lv77hnl0ebdq0.png)
The shear stress can be calculated by applying the Navier-Stokes equations and also can be expressed in other coordinates systems like cylindrical or spherical coordinates system.