Flow speed

As in freshwater, stagnation of seawater has an unfavourable effect on the corrosion resistance of aluminium. Agitation of seawater tends to improve the corrosion resistance and leads to a decrease in pitting depth. The experience with heat exchangers of seawater 

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Since aerothermal performance of compressors and turbines is very sensitive to inlet temperature and pressure variations, it is essential to normalize the aerothermal performance parameters such as flow, speed, horsepower, etc., to standard-day conditions. When these corrections to standard conditions are not applied, a performance degradation may appear to occur when in fact it was a performance change resulting merely from ambient pressure and temperature changes. Some of the equations for obtaining correction to standard-day conditions are given in Table 19-3. 

Harlow, F. H., and A. A. Amsden. 1971. A numerical fluid dynamics calculation method for all flow speeds. J. of Computational Physics. 8(2) 197-213. 

At flow speeds well below the speed of sound, the lift coefficient depends only on the shape and orientation (angle of attack) of the body ... 

From the image sequences, information on the velocities of nano-particles can be extracted. The statistical effect of Brownian motion on the flowing speed of the mixed liquid is found small enough to be ignored as shown in Fig. 37 where most of the particles trajectories in the liquid are straight lines and parallel with the wall basically. Therefore, Brownian diffusive motion is ignorable. 

In the case where the material used to make the capillary tube is a soft rubber, Eq. (46) does not apply any more, due to the viscoelastic braking induced by the displacement of the wetting ridge. The viscoelastic braking force, / per unit of length of the triple line depends on the flow speed U according to ... 

A bench top polysulfone hollow fiber membrane (0.0325m ) with molecular weight cutoff (MWCO) of 30K (A/G Technology Corp., Needham MA) was used (24). UF was run in a total recycle mode at a rate of 1.2 L/min (flow speed of 0.73 m/sec), cross membrane pressure of 25 PSIG and 10 + 1°C. PE permeability is expressed as the fraction of PEU/mL in the permeate to PEU/mL in the retentate. Data presented are representative of at least duplicate replications. 

In choosing a model, the user can optimize fate assessment efforts by delineating first, the source release patterns and second, the dominant dynamical processes. Taking the intramedia processes first, one can address model criteria by considering the ratio of characteristic times. The advection time is the principal length scale of the domain L divided by the average flow speed u i.e. 

FIGURE 11.32 Flow profiles in microchannels, (a) A pressure gradient, - AP, along a channel generates a parabolic or Poiseuille flow profile in the channel. The velocity of the flow varies across the entire cross-sectional area of the channel. On the right is an experimental measurement of the distortion of a volume of fluid in a Poiseuille flow. The frames show the state of the volume of fluid 0, 66, and 165 ms after the creation of a fluorescent molecule, (b) In electroosmotic flow in a channel, motion is induced by an applied electric field E. The flow speed only varies within the so-called Debye screening layer, of thickness D. On the right is an experimental measurement of the distortion of a volume of fluid in an electroosmotic flow. The frames show the state of the fluorescent volume of fluid 0, 66, and 165 ms after the creation of a fluorescent molecule [165], Source http //www.niherst.gov.tt/scipop/sci-bits/microfluidics.htm (see Plate 12 for color version). 

An illustration of the three methods is given for the problem of incompressible flow over a flat plate. The flow is steady and two-dimensional, as shown in Figure 12.1, with the approaching constant flow speed designated as u00. 

The combustion wave of a premixed gas propagates with a certain velocity into the unburned region (with flow speed = 0). The velocity is sustained by virtue of thermodynamic and thermochemical characteristics of the premixed gas. Figure 3.1 illustrates a combustion wave that propagates into the unburned gas at velocity Mj, one-dimensionally under steady-state conditions. If one assumes that the observer of the combustion wave is moving at the same speed, Wj, then the combustion wave appears to be stationary and the unburned gas flows into the combustion wave at the velocity -Wj. The burned gas is expelled downstream at a velocity of-M2 with respect to the combustion wave. The thermodynamic characteristics of the combustion wave are described by the velocity (u), pressure (p), density (p), and temperature (T) of the unburned gas (denoted by the subscript 1) and of the burned gas (denoted by the subscript 2), as illustrated in Fig. 3.1. 

Fast-flow systems (FFS) consist of a flow tube typically 2- to 5-crn in diameter in which the reactants A and B are mixed in the presence of a large amount of an inert bath gas such as He or Ar. As the mixture travels down the flow tube at relatively high linear flow speeds (typically 1000 cm s l), A and B react. The decay of A along the length of the flow tube, that is, with time, is followed and Eq. (T) applied to obtain the rate constant of interest. 

The term fast flow comes from the high flow speeds. In most of these systems, discharges are used to generate A or another species that is a precursor to A hence the term fast-flow discharge system (FFDS) is also commonly applied. Since fast-flow discharge systems have been applied in many kinetic and mechanistic studies relevant to tropospheric chemistry (e.g., see Howard, 1979 Kaufman, 1984), we concentrate on them. However, all fast-flow systems rely on the same experimental and theoretical principles. 

Here v is the linear flow speed, which can be calculated from the cross-sectional area of the flow tube (Ar), the total pressure (P) in the flow tube, the temperature (T), and the molar flow rates (dn / dt) of the reactants and the diluent gas ... 

At typical linear flow speeds of 1000 cm s l, 1 cm along the tube corresponds to 1-ms reaction time. Thus a flow tube of length 1 m can be used to study reactions at reaction times up to 100 ms. 

Rate Variables, These variables are concerned with the rate at which a body is moving toward or away from a fixed point. Time always is a component of a rate variable. Variables included are flow, speed, velocity, and acceleration. 

In the continuum flow regime the mean free path X is much smaller than the orifice diameter, and the exit pressure from the reactor is orders of magnitude greater than the backing pressure in the ion source vacuum chamber. The Mach number is unity that is, the flow speed, t , through the orifice is sonic ... 

It was established experimentally that a jet-type of flow appears when the characteristic size of the stream is less than the minimal gap between the walls of the mold.277 This proves that the cause is related to the ratio between the size of the injection nozzle and the coefficient of swelling of the elastic liquid moving inside the mold rather than to the axial momentum of the moving liquid. This conclusion is also supported by evidence that highly filled polymers, which are less elastic than pure melts, form jet-like patterns at lower flow speeds. 

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