Dynamic velocity ratio

DVR dynamic velocity ratio EDM electric discharge machining... 

DVR dynamic value research DVR dynamic velocity ratio... 

The static Poisson ratio is determined in a triaxial cell. The dynamic Poisson ratio is calculated with the sonic compressional and shear wave velocities. They usually are different. 

Following the convention used in gas dynamics, we will define the velocity ratio and disperse-phase Knudsen number differently according to whether the disperse phase is subsonic or supersonic ... 

The density of water is 1000 kg and to achieve the same dynamic velocity in air as water, the air velocity will equal the product of the water velocity and the square root of the ratio of the densities ... 

These dynamic moduli correspond to the initial tangent moduli of the stress-strain curve for an instantaneously applied load and are usually higher than those obtained in static tests. The frequency and nature of discontinuities within a rock mass affect its deformability. In other words, a highly discontinuous rock mass exhibits a iower compressional wave velocity than a massive rock mass of the same type. The influence of discontinuities on the deformability of a rock mass can be estimated from a comparison of its in situ compressional velocity, /pf, and the laboratory sonic velocity, /p, determined from an intact specimen taken from the rock mass. The velocity ratio, /pf/t/pi, reflects the deformability and so can be used as a quality index. A comparison of the velocity ratio with other rock quality indices is given in Table 2.7. 

For spherical particles, Bourgeois and Grenier (1968) proposed semitheoretical correlations relating the ratio of terminal velocity to minimum fluidizing velocity with the Arehimedes number, Ar, as shown in Eqs. (59) through (64). Depending on whether the fluidized bed is fluidized by air or water, the velocity ratios are slightly different. The terminal velocity of a solid particle has been discussed in Sec. 4 of Chapter 1, Particle Characterization and Dynamics. ... 

In this paper a full numerical solution for the non-steady-atate EHD problem in line contacts is presented and the method of computation also described The pressure distributions and film shapes are obtained for a number of the normal-to -en-training-velocity ratios. The dynamic behavior of lubricant film, for both normal approaching and separation motion Is investigated and discussed. Based on the numerical results, a formula for estimating the dynamic film thickness is developed. 

In order to simulate the action of a flow on an adhering particle we must maintain geometric, kinematic (velocity ratio), and dynamic (mass and force) similarity. We cannot choose these conditions in detail. We can only note that for river-type flows the Froude criterion Fr = v /gZ ensures d5mamic similarity and the Reynolds criterion Re = vd/ v kinematic similarity. Since the forces of gravity prevail over viscosity, the decisive factor in simulating river flows will be the Froude criterion. 

Dynamic velocity range (DVR) is related to the fundamental velocity resolution and hence the accuracy of PIV measurement. DVR specifies the range of velocity over which measurements can be made. It is the ratio of the maximum velocity to the minimum resolvable velocity or equivalently the root mean square (rms) error in the velocity measurement, that is. 

The absolute or dynamic viscosity is defined as the ratio of shear resistance to the shear velocity gradient. This ratio is constant for Newtonian fluids. 

Let H and L be two characteristic lengths associated with the channel height and the lateral dimensions of the flow domain, respectively. To obtain a uniformly valid approximation for the flow equations, in the limit of small channel thickness, the ratio of characteristic height to lateral dimensions is defined as e = (H/L) 0. Coordinate scale factors h, as well as dynamic variables are represented by a power series in e. It is expected that the scale factor h-, in the direction normal to the layer, is 0(e) while hi and /12, are 0(L). It is also anticipated that the leading terms in the expansion of h, are independent of the coordinate x. Similai ly, the physical velocity components, vi and V2, ai e 0(11), whei e U is a characteristic layer wise velocity, while V3, the component perpendicular to the layer, is 0(eU). Therefore we have... 

There are certain limitations on the range of usefulness of pitot tubes. With gases, the differential is very small at low velocities e.g., at 4.6 m/s (15.1 ft/s) the differential is only about 1.30 mm (0.051 in) of water (20°C) for air at 1 atm (20°C), which represents a lower hmit for 1 percent error even when one uses a micromanometer with a precision of 0.0254 mm (0.001 in) of water. Equation does not apply for Mach numbers greater than 0.7 because of the interference of shock waves. For supersonic flow, local Mac-h numbers can be calculated from a knowledge of the dynamic and true static pressures. The free stream Mach number (MJ) is defined as the ratio of the speed of the stream (V ) to the speed of sound in the free stream ... 

Another velocity finally appears in a system where a liquid is in contact with an interface. The interface energy 7 then works as a static driving force. This can trigger a current which is damped by a dynamic force, the viscous friction, in the case of density difference between crystal and liquid. Taking the ratio... 

A detonation shock wave is an abrupt gas dynamic discontinuity across which properties such as gas pressure, density, temperature, and local flow velocities change discontinnonsly. Shockwaves are always characterized by the observation that the wave travels with a velocity that is faster than the local speed of sound in the undisturbed mixtnre ahead of the wave front. The ratio of the wave velocity to the speed of sound is called the Mach number. 

To overcome this problem, they proposed a working-fluid heat-addition model. This model implies that the gas dynamics are not computed on the basis of real values for heat of combustion and specific heat ratio of the combustion products, but on the basis of effective values. Effective values for the heat addition and product specific heat ratios were determined for six different stoichiometric fuel-air mixtures. Using this numerical model, Luckritz (1977) and Strehlow et al. (1979) systematically registered the properties of blast generated by spherical, constant-velocity deflagrations over a large range of flame speeds. 

Because the most common impeller type is the turbine, most scale-up published studies have been devoted to that unit. Almost all scale-up situations require duplication of process results from the initial scale to the second scaled unit. Therefore, this is the objective of the outline to follow, from Reference [32]. The dynamic response is used as a reference for agitation/mixer behavior for a defined set of process results. For turbulent mixing, kinematic similarity occurs with geometric similarity, meaning fixed ratios exist between corresponding velocities. 

The mechanical efficiency of a fan is the ratio of the horsepower output to the horsepower input at the fan shaft. The input horsepower to drive the fan consists of the air horsepower, the energy losses in the fan, fluid dynamic losses, shock losses, leakage, disk friction, and bearing losses (all as horsepower), The fan oudet velocity pressure loss has been included in the fluid dynamic losses. 

Pandey et al. have used ultrasonic velocity measurement to study compatibility of EPDM and acrylonitrile-butadiene rubber (NBR) blends at various blend ratios and in the presence of compa-tibilizers, namely chloro-sulfonated polyethylene (CSM) and chlorinated polyethylene (CM) [22]. They used an ultrasonic interferometer to measure sound velocity in solutions of the mbbers and then-blends. A plot of ultrasonic velocity versus composition of the blends is given in Eigure 11.1. Whereas the solution of the neat blends exhibits a wavy curve (with rise and fall), the curves for blends with compatibihzers (CSM and CM) are hnear. They resemble the curves for free energy change versus composition, where sinusoidal curves in the middle represent immiscibility and upper and lower curves stand for miscibihty. Similar curves are obtained for solutions containing 2 and 5 wt% of the blends. These results were confirmed by measurements with atomic force microscopy (AEM) and dynamic mechanical analysis as shown in Eigures 11.2 and 11.3. Substantial earher work on binary and ternary blends, particularly using EPDM and nitrile mbber, has been reported. 

Flames submitted to convective disturbances experience geometrical variations, which can in turn give rise to heat release unsteadiness. This process can be examined by considering different types of interactions between incident velocity or equivalence ratio modulations and combustion. The flame dynamics resulting from these interactions give rise to sound radiation and... 

Flame velocity versus fuel concentration for H2/air mixtures in the 10 m long tubes of 5, 15, and 30 cm internal diameter with obstacles (orifice plates) BR = 1 - d /D - blockage ratio, where d is the orifice diameter and D is the tube diameter. (From Lee, J.H., Advances in Chemical Reaction Dynamics, Rentzepis, P.M. and CapeUos, C., Eds., 246,1986.)... 

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