Viscosity is the property of a fluid that resists its flow. It is caused by the intermolecular forces between the fluid molecules.

Hydrostatic pressure is the pressure exerted by a fluid at a given point due to the weight of the fluid above it.

Pascal's law states that pressure applied to a fluid in a closed container is transmitted equally to every point in the fluid.

Buoyant force is the upward force exerted by a fluid on an object immersed in it. It is equal to the weight of the fluid displaced by the object.

Bernoulli's principle states that the total energy of a fluid flowing in a pipe remains constant, provided there is no energy loss due to friction or other factors.

Poiseuille's equation describes the relationship between flow rate, pressure drop, and resistance in a pipe. It is used to calculate the flow rate of a fluid through a pipe.

Laminar flow is a type of fluid flow in which the fluid flows in layers, with each layer moving at a different velocity. In laminar flow, the fluid particles move in smooth, parallel paths.

Turbulent flow is a type of fluid flow in which the fluid flows in a chaotic and unpredictable manner. In turbulent flow, the fluid particles move in irregular and fluctuating paths.

Boundary layer flow is the layer of fluid near a solid surface where the flow is affected by the surface. In boundary layer flow, the fluid particles are slowed down by the surface and the flow becomes laminar.

Couette flow is a type of fluid flow where a fluid flows between two parallel plates with a constant velocity. In Couette flow, the fluid particles move in parallel layers, with each layer moving at a different velocity.

Drag force is the force exerted by a fluid on a moving object in the direction opposite to the motion. It is caused by the friction between the fluid and the object.

Lift force is the force exerted by a fluid on an object in a direction perpendicular to the motion. It is caused by the difference in pressure between the two sides of the object.

Thrust force is the force exerted by a fluid on an object in the direction of the motion. It is caused by the acceleration of the fluid by the object.

Hydraulics is the study of the flow of fluids in pipes and channels. It is a branch of fluid mechanics that deals with the practical applications of fluid flow.

Pneumatics is the study of the flow of gases. It is a branch of fluid mechanics that deals with the practical applications of gas flow.