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Here the pressure P D is referred to as dynamic pressure due to the kinetic energy of the fluid experiencing relative flow velocity u. This is defined in similar form as the kinetic energy equation: P D = 1 2 ρ u 2 {\displaystyle P_{\rm {D}}={\frac {1}{2}}\rho u^{2}}
For stationary, creeping, incompressible flow, i.e. D(ρu i) / Dt ≈ 0, the Navier–Stokes equation simplifies to the Stokes equation, which by neglecting the bulk term is: =, where μ is the viscosity, u i is the velocity in the i direction, and p is the pressure. Assuming the viscous resisting force is linear with the velocity we ...
Drag coefficients in fluids with Reynolds number approximately 10 4 [1] [2] Shapes are depicted with the same projected frontal area. In fluid dynamics, the drag coefficient (commonly denoted as: , or ) is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water.
If correctly selected, it reaches terminal velocity, which can be measured by the time it takes to pass two marks on the tube. Electronic sensing can be used for opaque fluids. Knowing the terminal velocity, the size and density of the sphere, and the density of the liquid, Stokes' law can be used to calculate the viscosity of the fluid. A ...
Stated formally, in general, an equation of motion M is a function of the position r of the object, its velocity (the first time derivative of r, v = dr / dt ), and its acceleration (the second derivative of r, a = d 2 r / dt 2 ), and time t. Euclidean vectors in 3D are denoted throughout in bold.
v d is the magnitude of the electron drift velocity (in other words, the electron drift speed) caused by the electric field, and; μ e is the electron mobility. The hole mobility is defined by a similar equation: =. Both electron and hole mobilities are positive by definition.
The Reynolds number Re is taken to be Re = V D / ν, where V is the mean velocity of fluid flow, D is the pipe diameter, and where ν is the kinematic viscosity μ / ρ, with μ the fluid's Dynamic viscosity, and ρ the fluid's density. The pipe's relative roughness ε / D, where ε is the pipe's effective roughness height and D the pipe ...
The discharge formula, Q = A V, can be used to rewrite Gauckler–Manning's equation by substitution for V. Solving for Q then allows an estimate of the volumetric flow rate (discharge) without knowing the limiting or actual flow velocity. The formula can be obtained by use of dimensional analysis.