API RP 13D:2003 pdf download

API RP 13D:2003 pdf download.Recommended Practice on the Rheology and Hydraulics of Oil-well Drilling Fluids.
4 Basic Concepts
4.1 FLOW REGIMES
4.1.1 The behavior of a fluid is determined by the flow regime. which in turn has a direct effect on the ability of that fluid to perform its basic functions. The flow can be either laminar or turbulent, depending on the fluid velocity, size and shape of the flow channel. fluid density, and viscosity. Between laminar and turbulent flow, the fluid will pass through a transition region where the movement of the fluid has both laminar and turbulent characteristics. It is Important to know which of the flow regimes is present in a particular situation to evaluate the performance of a fluid.
4.1.2 In laminar flow, the fluid moves parallel to the walls of the flow channel in smooth lines. Flow tends to be laminar when moving slowly or when the fluid is viscous. In laminar flow, the pressure required to move the fluid increases with increases in the velocity and viscosity.
4.1.3 In turbulent flow, the Iluid is swirling and eddying as it moves along the flow channel, even though the bulk of the fluid moves forward, These velocity fluctuations arise spontaneously. Wall roughness or changes in flow direction will increase the amount olturbulence. Flow tends to be turbulent with higher velocities or when the fluid has low viscosity. In turbulent flow, the pressure required to move the fluid increases linearly with density and approximately with the square of the velocity. This means more pump pressure is required to move a fluid in turbulent flow than in laminar flow.
4.1.4 The transition between laminar and turbulent flow is controlled by the relative importance of viscous forces and inertial forces in the flow. In laminar flow, the viscous forces dominate, while in turbulent flow the inertial forces are more important. For Newtonian fluids, viscous forces vary linearly with the flow rate, while the inertial forces vary as the square of the flow rate.3
4.1.5 The ratio of inertial forces to viscous forces is the Reynolds number. If consistent units are chosen, this ratio will he dimensionless and the Reynolds number (Re) will be.