Average fluid velocity

D. Diameter of curvature m V Characteristic or average fluid velocity m/s... 

The one-particle distribution function fp specifies both the total particle density p and momentum density pu, where u is the average fluid velocity. 

Fig. 60. Degradation yield as a function of volumetric average fluid velocity at the orifice (v (symbols are the same as used in Fig. 58).

Consider isothermal laminar flow of a Newtonian fluid in a circular tube of radius R, length L, and average fluid velocity u. When the viscosity is constant, the axial velocity profile is... 

The first example pertains to forced convection in pipe flow. It is found that the rate of heat transfer between the pipe wall and a fluid flowing (turbulent flow) through the pipe depends on the following factors the average fluid velocity (u) the pipe diameter (d) the... 

For a Newtonian fluid in a smooth pipe, these equations can be integrated over the pipe cross section to give the average fluid velocity, e.g.,... 

V average fluid velocity vector (in RANS context)... 

Uc Average fluid velocity based on cross-sectional area A of m/s LT-1... 

V = average fluid velocity through bed D = granule diameter fr = granule shape factor g = gravitational constant t = time... 

Equal liquid motion (equal average fluid velocity)... 

Velocity is a relatively simple and intuitive concept for a solid body. Because a fluid is continuously deformable, however, defining its velocity takes a bit more care. At a molecular scale a fluid is a collection of particles. In principle, one can describe the velocity of a fluid in terms of the velocities of each molecule in the fluid. Obviously this would be impractical owing to the extreme numbers of molecules that would have to be considered. Instead, it is appropriate to use a velocity field that represents an the average fluid velocity at every point within the fluid. 

If we express the free cross-section of the column bed by the interparticle porosity (knowing total porosity of packed beds with porous particles is larger because of intraparticle space), we can obtain the true average fluid velocity, v,... 

To simplify the derivation, we may consider only the one-dimensional case. Denote s(to +1 ) as the distance traveled by a marked fluid element with starting time t0 during the time interval t. Let u be the instantaneous velocity and u be the fluctuating velocity. In the following derivation, the time-averaged fluid velocity is taken as zero. Thus, we have... 

U the open-circuit value oi [Pg.294]

A schematic of the flow-through nanohole array concept is shown in Fig. 13a. Figure 13b shows computationally predicted biomarker transport within the nanoholes for in-hole average fluid velocities of 1 pm/s and 1 cm/s (as indicated). Reaction rate constants characteristic of surface-based antibody-antigen reactions (with reaction rate constant k - 10 /M/s) [69] were applied at the nanohole walls. For the low average velocity, diffusion of the biomarker (with diffusivity D - 4x10 m s ) to the nanohole surface is effectively complete in one diameter. This result reflects the rapid diffusion characteristic of nanoconfinement. For the higher flow rate case, the absorption of the analyte stream is delayed however, over 90% bulk adsorption of analyte is attained with the flow rates and nanohole... 

---