divergence of the velocity vector field C on that volume: \iint_S\mathbf{C}\cdot d\mathbf{S}=\iiint_C\left(\nabla\cdot\mathbf{C}\right)dV . Fluid mechanics Fluid mechanics is the study of fluid s and the force s on them. (Fluids include liquid s, gas es, and plasma s.) Fluid mechanics can be divided into fluid kinematics, the study of fluid motion,