Kidphysics said:So I understand that Reynolds number is the ratio of intertial forces to viscous forces but how exactly does this relate to flow? Why is it that when viscous forces dominate one gets a laminar flow? How to conceptualize?
Chestermiller said:High viscosity tends to damp out turbulent energy fluctuations.
The Reynolds number is a dimensionless quantity that characterizes the ratio of inertial forces to viscous forces in a fluid flow. It is important in fluid dynamics because it helps determine the type of flow (laminar or turbulent) that will occur in a given situation.
The Reynolds number is calculated by multiplying the fluid velocity by the characteristic length of the flow (such as diameter of a pipe) and dividing it by the kinematic viscosity of the fluid. The resulting value is a dimensionless number that is used to predict flow behavior.
The Reynolds number is directly related to the occurrence of laminar flow. When the Reynolds number is low (less than 2300), the flow is considered laminar, meaning the fluid particles move in smooth, parallel layers with little mixing. As the Reynolds number increases, the flow becomes more turbulent.
As mentioned earlier, the Reynolds number is directly related to the occurrence of turbulent flow. When the Reynolds number is high (greater than 4000), the flow is considered turbulent, meaning the fluid particles mix and swirl chaotically. This type of flow is characterized by eddies and vortices.
The Reynolds number also has an impact on the amount of drag force experienced by an object in a fluid flow. At low Reynolds numbers, the drag force is proportional to the velocity of the object. However, at high Reynolds numbers, the drag force is proportional to the square of the velocity, meaning it increases significantly with increasing velocity.