A first-order fluid, also known as a Newtonian fluid, is a type of fluid that adheres to Newton's law of viscosity. This means that the fluid's shear stress is directly proportional to the shear rate (or velocity gradient) at a given temperature and pressure. Mathematically, this relationship is represented as: \[ \tau = \mu \frac{du}{dy} \] Where: - \(\tau\) is the shear stress.
New to topics? Read the docs here!