Drift velocity average values

DMSO, molecular models, 17 DNA, and dielectric behavior, 195 Drag forces, acting on ion, 452 Drift velocity average values of, 443 and the effect of the unsymmeuical ionic atmosphere, 510... 

Average values are based on typical efficiencies of precipitators purchased. Drift velocities will drop if higher efficiencies are required. Recomputed from data of reference 175. 

The average value of drift velocity, um, is given by integration of Eq. (79) over the radius of the tube according to the relevant mean value theorem,... 

The drift velocity and diffusivity for a Stratonovich SDE may be obtained by using Eq. (2.239) to calculate the first and second moments of AX to an accuracy of At). To calculate the drift velocity, we evaluate the average of the RHS of Eq. (2.244) for AX . To obtain the required accuracy of At), we must Taylor expand the midpoint value of that appears in Eq. (2.244) to first order in AX about its value at the initial position X , giving the approximation... 

To evaluate the drift velocity, we take the average of Eq. (2.315) for AX , while Taylor-expanding the midpoint value of D P to first order in AX about its value at X . This yields... 

Any particular ion starts off after a collision with a velocity that may be in any direction this is the randomness in its walk. The initial velocity can be ignored precisely because it can take place in any direction and therefore does not contribute to the drift (preferred motion) of the ion. But the ion is all the time under the influence of the applied-force field. This force imparts a component to the velocity of the ion, an extra velocity component in the same dkection as the force vector F. It is this additional velocity component due to the force F that is called the drift velocity Vj. What is its average value ... 

The average value of that component of the velocity of an ion picked up from the externally applied force is the product of the acceleration due to this force and the average time between collisions. Hence, the drift velocity Vj is given by... 

With the term w representing the effective migration or drift velocity. (Note wA/q is often denoted as numerical value of w is selected on the basis of experience with a particular dust, a particular set of operating conditions, and a particular design. Precipitator manufacturers usually have a specific experience file from which the precipitation rate parameter can be selected for various applications and conditions. Average values of precipitation rate parameters for various applications, and the range of values that might be expected, are presented below. 

Since the absorbent flows continuously from plate to plate and is also repeatedly diluted by the absorbent coming out of the elements, the state of the absorbent layered on the plates can be characterized by residence times inside the element tg = Lgfug, and at the plate f = V/Qa, where V is the absorbent volume at the plate, Lg is the height of the element, Q is the absorbent flow rate, and Ug is the average vertical drift velocity of the gas inside the element (i.e. velocity along the symmetry axis of the element). A comparison of these two times for the characteristic parameter values shows that tg t). This means as it dwells at the plate, the absorbent has enough time to make numerous contacts with the gas inside the elements installed on this plate. 

It was found that doubling the source drift velocity decreased the extent of reaction by 15% for C3H6 at thermal energy, and so the energy scale used for Fig. 14 probably has a built-in error of at least 10-20% (i.e., the average energy of the reacting ions is at least 10-20% lower than the calculated value). 

This is further evidence that the free drift velocity is saturated Furthermore from the previously established value for v one deduces that s the average intertrap sepeuration is 1.1 mm, a value similar to that found by two independent routes (1,2)... 

A record of the axial velocity component vx for steady turbulent flow in a pipe would look like the trace shown in Figure 1.22. The trace exhibits rapid fluctuations about the mean value, which is determined by averaging the instantaneous velocity over a sufficiently long period of time. Figure 1.22 shows the case in which the mean velocity remains constant this is therefore known as steady turbulent flow. In unsteady turbulent flow, the mean value changes with time but it is still possible to define a mean value because, in practice, the mean will drift slowly compared with the frequency of the fluctuations. 

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