STEADY-STATE PREDICTIONS BASED ON FIRST DOSE DATA

1992 ◽  
Vol 15 ◽  
pp. 239A-240A
Author(s):  
W. Z. POTTER ◽  
C. LINDSAY DeVANE ◽  
M. V. RUDORFER
Author(s):  
Euro L. Casanova ◽  
Luis U. Medina

This paper deals with the dynamics of an accelerating unbalanced Jeffcott rotor-bearing system mounted on damped, flexible supports. The general equations of motion for such a system are presented and discussed. The rotor response was predicted, via numerical integration, for various cases in runup and rundown conditions and presented in graphical form. The effects of acceleration on the rotor peak amplitude and the speed at which the peak occurs is discussed and compared to steady state predictions.


Author(s):  
K. M. Akyuzlu ◽  
J. Farkas

An experimental study was conducted to observe/visualize, the formation of circulation patterns inside a square cavity due to the movement of a lid at constant velocity. Lid driven cavity flow is one of the benchmark studies used in the verification/improvement of CFD codes for internal flow applications/predictions. Previous work on this topic is primarily focused on improving the steady state predictions of the CFD codes using different numerical schemes and algorithms. Furthermore, almost all of the studies reported in computational fluid mechanics literature relates to steady state predictions of lid or shear driven flows. Experimental work that is reported in these studies is limited in scope and number. This paper reports on the measurements we made using Particle Image Velocimeter (PIV) technique to determine the flow field as it develops from stagnation to steady state inside a square cavity driven by a lid. For this purpose, we employed a 2-D PIV system, which uses a double-cavity, Nd:Yag laser to illuminate the test cavity. Experiments were conducted using water as the working fluid inside a square cavity that is one inch (25.4 mm) high and one inch wide. The depth of the cavity is five inches (127 mm) to ensure two-dimensional circulations patterns. Hollow glass sphere particles with 10 microns in diameter were used as seeding of the working fluid, water. Experiments were repeated for different lid velocities corresponding to lid Reynolds numbers (laminar to beginning of transition of turbulence.) Velocity fields were captured during the development of the circulations patters each being unique for the time of the measurement and value of the lid velocity. The center of the circulation pattern and its path inside the cavity is constructed from the captured images as steady state is attained. Also, the strength of the circulation (as manifested by the increase in the diameter of the circulation) is determined at different times for different Reynolds numbers.


2001 ◽  
Vol 123 (5) ◽  
pp. 506-512 ◽  
Author(s):  
Matthew R. Myers ◽  
Bigyani Das

Although synthetic membranes such as gloves, condoms, and instrument sheaths are used in environments with highly time-varying stresses, their effectiveness as barriers to virus transmission is almost always tested under static conditions. In this paper it is shown how a previously developed mathematical model can be used to transform information from static barrier tests into predictions for more realistic use conditions. Using a rate constant measured for herpes adsorption to latex in saline, and an oscillatory trans-membrane pressure representative of coitus, the amount of virus transmitted through a hole (2 μm diameter) in a condom is computed. Just beyond the exit orifice of the pore, transport is dominated by the rapidly dissipating viscous jet of virus suspension, which results in an accumulation of viruses roughly 20 pore radii from the barrier surface during each cycle. Due to virus adsorption to the barrier surfaces, the simulations reveal a gradual decrease in virus flow with increasing number of cycles, and thus a slow divergence from predictions based upon steady-state conditions. Still, over the 500 cycles simulated, steady-state predictions approximate the net number of viruses transmitted to within 25 percent error.


1975 ◽  
Vol 97 (3) ◽  
pp. 347-351 ◽  
Author(s):  
V. K. Dhir

An experimental study of laminar film condensation of steam on copper spheres of 1.90, 2.54, and 3.17 cm dia has been made. Experiments have been performed by submerging cold spheres in nearly stagnant water vapor at a saturation temperature of about 99° C. Values of Nusselt number based on average heat transfer coefficient are obtained for saturation to wall temperature differences of 5–65° C and for cp ΔT/hfg in the range of 0.009–0.12. The data are compared with the steady-state predictions of Dhir and Lien-hard and of Yang. Analysis has been made to show that it is valid to use steady-state solutions in quasi-steady condensation as long as the dimensionless thermal diffusion time constant is small, and the film does not move very slowly.


1993 ◽  
Vol 115 (1) ◽  
pp. 191-199 ◽  
Author(s):  
C. J. Hooke

In contacts, such as cams, non-involute gears and shaft seals, where the direction of entrainment reverses during the operating cycle, the minimum film thickness is typically found just after the reversal. This paper shows that this minimum film thickness is determined by the rate of change of the entraining velocity and by the fluid and surface properties. For line contacts, four regimes of lubrication are found—as for the steady-state situation—and expressions for the film thickness in each regime are developed. This enables an outline design chart for the minimum film thickness to be constructed. It is shown that this information, together with the steady-state predictions is sufficient to determine the variation of film thickness with time in most situations where load, radius of curvature, and entraining velocity vary.


AIChE Journal ◽  
1977 ◽  
Vol 23 (1) ◽  
pp. 120-123 ◽  
Author(s):  
S. C. Foo ◽  
R. G. Rice

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