There are three numerical processes that include solving Reynolds equation to find hydrodynamicpressure distribution on the piston skirt surface, getting the solution based on viscoelastic property of fluid (Deborah number, De) by computing corrections of the solution at order De for the pressure (Deborah number De is always less than unity ) and incorporation of small corrections from the effects of geometric parameter . The asymptotic solution to the exact formulation of the Upper Convected Maxwell model is the sum of conventional lubrication solution plus solution based on viscoelastic property of fluid and incorporation of small stated corrections.
Abstract: Nanopores with irregularities are promising tools for distinguishing nano-size objects by their shape, but the forces on the object that critically influence its axial and rotational movement are unclear. The physics of the situation was described using the Poisson-Nernst-Planck and Navier- Stokes equations. With uniformly charged object the axial Coulomb and dielectric pressure (which opposes it and is surprisingly important), control the object's axial movement and rotation. Even without external pressure the hydrodynamicpressure is significant (negative at its upper and positive at its lower surface), but its total value is almost zero. If the object is charged only on the upper surface the axial upper Coulomb pressure is near zero close to the center, but negative near its end (the pressure is zero at the lower surface). The total axial dielectric pressure, which is largely dominated by the pressure at the upper surface, is positive along the length of the object becoming pronounced near its end. The axial hydrodynamicpressure is negative and significant at the upper surface (zero at the lower surface), diminishes in value near the object's end, critically influencing its axial movement, which becomes much faster. At its end the axial dielectric pressure prevails, and controls its rotation.
When a tank containing liquid vibrates, the liquid exerts impulsive and convective hydrodynamicpressure on the tank wall and the tank base in addition to the hydrostatic pressure. In order to include the effect of hydrodynamicpressure in the analysis, tank can be idealized by an equivalent spring mass model, which includes the effect of tank wall – liquid interaction. The parameters of this model depend on geometry of the tank and its flexibility.
Thus, the received results testify more expressed disorders of parameters of microcirculation of a liver where hydrodynamicpressure is slightly lower than in the system of peripheral blood circulation of a cortical layer of kidneys. The explanation of this phenomenon can be found in the features of action of high concentration of the thyroid hormones. The change of thyroid function leads to endothelial dysfunction and disorder of a thin balance in the system of coagulation and fibrinolysis. These aspects of pathogenesis of the hyperthyroid states also define more expressed disorders of microcirculation in liver where the hydrodynamicpressure of blood and linear speed of blood-groove is significantly lower than in kidneys. The important role is also played by features of blood supply of a liver, receiving ¾ of blood on portal system and kidneys whose blood supply is carried out directly from belly department of an aorta.
When analysis of a bearing was done using Reynolds Equation, Reynolds equation governs the pressure distribution around the circumference of journal in the clearance space of fluid film bearing. It is used to plot the Pressure profile in the hydrodynamic fluid film theory.The coordinate system and the geometry of fluid film journal bearing is shown in Fig. 1. An equilibrium position under the external load is attended due to the hydrodynamicpressure generated by the lubricant film through journal rotates with an angular velocity ω.
The fluid in the container interacts with the container structure under the earthquake, and the bottom and the side walls are subjected to the pressure because of the fluid sloshing. This pressure is called hydrodynamicpressure. The Lumped Mass-Spring Model(LMSM) is presented in “Seismic Analysis of Safety related Nuclear Structures and Commentary on Standard for Seismic Analysis of Safety related Nuclear Structures”  (ASCE 4-86). This model, which is simple but valid, is described in detail. This paper develops 3-D mass-spring model based on the LMSM in the ASCE4-86. Moreover, the mass-spring model linked to the bottom of the container is given to simulated the pressure on the bottom.
the inertial forces of the wall in addition to the hydrodynamicpressure of the contained liquid. The contained liquid can be divided into two parts: the first part is mainly the lower amount of liquid, which moves with the walls of the tank and is called the impulsive liquid mass. The second part is mainly the upper amount of liquid and is called the convective liquid mass, which undergoes sloshing due to vibration. The ratio of the convective mass to the impulsive one increases as the tank becomes shallower. Also, the frequency of the impulsive vibration modes is much higher than those of the convective vibration mode. The first study related to steel conical tanks was conducted by Vandepitte et al. (1982) after the collapse of a conical steel water tower in Belgium. In this study, a large number of small-scale conical tank models were tested experimentally under hydrostatic pressure. The models were gradually filled with water till buckling occurred. The test results were used to develop a set of design curves for different base restraining conditions. The effect of geometric imperfections on the safety factor of the conical tanks was also studied. In 1990, a steel conical water tower collapsed in Fredericton, Canada when it was filled with water for the first time. Vandepitte (1999) concluded that the main cause of failure was related to the inadequate thickness of the tank walls at the base. This was due to the designer’s underestimation of the amplitude of the geometric imperfections as their design was based on results obtained from the field of aerospace where a superior quality control takes place.
In the present work, an experimental study of the HD pressure in a journal bearing was carried out in case of varying of load and speed, using a specially designed test rig for this purpose. The results presented refer to the HD pressure distribution on the angular coordinate and the length of the bearing. In addition, the results are presented regarding the determination of the bearing torque at constant load and at various speeds. As noted above, the resulting trends of influencing the hydrodynamicpressure values from the change of shaft speed and the load change are identical to those obtained by other authors.
A calibration to assess maximum accessible Reynolds number was carried out by fixing the relaxation parameter u and increasing u through parameter uo, see section 5.2.1, for a set system size. Compressibility effects were found to be small from an inspection of the velocity field in the form of the contour plot of the stream function ip(x,y ), in the outlet of the channel, well behind the step, as shown in figure 5.8. In the exactly incompressible scheme, the streamlines of i/)(x, y) are parallel in this region and thus it may be inferred that the velocity field shows no evidence of systematic increase in u, as shown in figure 5.5 using a standard scheme to simulate duct flow. Moreover the pressure field shown in figure 5.8, from which the extent and non-uniformity of the variations is readily apparent, is fully consistent with uniform decay. This was observed to remain the case for all values of inlet profile parameter uo up to that which induced instability in the EILBGK simulation. A system of size 600 x 30 was driven with matched equilibrium forcing at inlet, and outlet, using a value of u) — 1.9 chosen as a compromise between low viscosity and stability. The value of b in use was determined on the basis of the value of /*, measured for flow in an infinite aspect ratio duct as in figure 5.3, again with u = 1.9.
The problem of acoustic-gravity wave propagation from variations in density and temperature on the Earth’s surface was studied mathematically in Kurdyaeva et al. (2018). The study showed that the variable pressure on the Earth’s surface uniquely determines the wave pattern, which however does not depend on the details of the temperature and density dy- namics on the Earth’s surface (Kurdyaeva et al., 2018). A nu- merical model of wave propagation from pressure variations on the Earth’s surface was developed in Kurdyaeva et al. (2018). The problem of wave propagation from pressure vari- ations set at the lower boundary is solved analytically in the case of an isothermal atmosphere. A test comparison of nu- merical and analytical solutions showed that the model (Kur- dyaeva et al., 2018) gives a very good agreement between the numerical solution and the analytical results. The numer- ical model was also used in Kshevetskii (2001a), Kshevetskii (2001b), Kshevetskii (2001c), and Kshevetskii (2002).
In the present work, CNTs were successfully synthesized over catalytic decomposition of the methane gas over bi metallic Co/Pd MgO supported. The CNTs which were obtained were of multiwalled morphology. Since the FBCVD reactor is used in this work, some factors affecting the production of CNTs such as pressure drop, minimum fluidization velocity and bed volume expansion were investigate. The volume bed expansion of carbon nanotubes was also studied and the effect of the N 2 :CH 4 flow rate ratio to obtain the highest
The arrangement of journal bearing system with bearing liner is shown in a schematic diagram (figure 1) above. Considering case of variable viscosity it has been observe most oils increases with pressure and the following relationship is assumed similar to Majumdar et.al. ,
A correction for flow swirl in the k-ε turbulence model is proposed. Accounting for this amendment made it possible to achieve agreement between the calculated and experimental data on the pressure distribution along the channel wall of the hydrodynamic generator, revealed the presence of cavitation in the generator under study, and made it possible to calculate the amplitude-frequency characteristics of the oscillations. In the absence of swirl, the presented model automatically changes to the standard one.
we can delineate hydrodynamic effects without pos- sible confounding effects of thrombosis within the aneurysm or on the pressure-temperature wire. Second, the silicone phantom allows rigorously de- signed studies at much greater precision than in vivo studies. In the phantom, all parameters can be exactly controlled and repeated to an almost un- limited extent. Apart from being more exact and reproducible as well as cheaper, the perfusion model may spare the life of many laboratory ani- mals, and hence, represents a tool for reduction, refinement, and replacement in accordance with the Guide to Searching for Alternatives to the Use of Laboratory Animals (11). Our silicone vascular model could thereafter be considered superior to those used in other dog experiments to evaluate the influence of changes in systemic pressure and pulse rate on aneurysmal flow and pressure. A latex vas- cular bench model or similar devices offer the unique opportunity for every neurointerventional- ist to try new, hands-on techniques before including them in their therapeutic armamentarium. In a model, the behavior of new materials can be stud- ied both by radiologic means and by direct obser- vation. Personal skills can be acquired without po- tential harm to patients. Furthermore, in elective cases, one could reconstruct latex models from 3D angiograms of patients and tailor the treatment of that particular patient.
When the H II region is inside approximately the ionized sonic point, where the flow velocity equals the local sound speed, it is unable to expand and remains gravitationally trapped. Accretion occurs from the infalling cold neutral gas and continues inwards towards the star through the H II region boundary where the gas forms an ionized accretion flow. As the star accretes mass, its luminosity increases and the H II region grows in size, not due to pressure driven expansion, but because of the increasing ionizing luminosity. Eventually the H II region will grow to surpass the critical radius close to the sonic point, gravity of the central star will no longer dominate, and the H II region will begin a pressure-driven expansion. At this stage, accretion through the ionization front can no longer occur. Some of the already ionized gas will move outwards along with the expanding ionization front, but the innermost gas continues to accrete on to the star, and as the H II region is drained accretion halts. This marks the maximum mass the star can accrete in a spherically symmetric system and beyond this stage the H II region continues its pressure-driven expansion.
________________________________________________________________________________________________________ Abstract— Hydrodynamic journal bearing is a vital component in the rotating machinery since efficiency of the machine greatly depends on the performance of the bearing. The journal bearing performs well for medium speed, but at high speed fluid starts to whip around the journal due to which constant wedge shape is not form. Hence journal becomes unstable and starts vibrating. To avoid this for high speed hydrodynamic journal bearing, shape of inner diameter of the bearing is changed such that it will try to avoid oil whip. One of the such method is providing lobes on inner surface of the bearing. Two lobe and multi lobe (more than two lobe) are the two methods to provide lobe on the bearing. The present paper is the validation of the theoretical results obtained by them using Computational Fluid Dynamics (CFD) software package ANSYS 14.5. Also comparison of variation of pressure around bearing surface of Two Lobe and Simple Hydrodynamic Journal Bearing is compared.
As a result of this study, it was found that the tapered pontoon system of this study presented more favorable hydrodynamic motions at incident wave of 45° and 90°, especially the pitch motion at the incident wave of 45°, than the uniform cross-sectional pontoon system. In respect of the wave-induced hydraulic pressure, the tapered pontoon system presented similar wave-induced hydraulic pressure ranges with the uniform cross-sectional pontoon system distributing locally onto the central part of the bottom slab.
The diesel pump compression energy released into the receiver during injection was converted to internal energy, resulting in large fuel temperatures in the receiver. Consequently, a temperature control system was installed in order to maintain the temperature of the diesel in the recirculation flow rig at a safe, steady-state value. The temperature control system was comprised of a thermocouple, a temperature controller and a counter-flow shell-and-tube heat exchanger. The thermocouple was located near the suction port of the high pressure stage of the high-pressure pump. The rate of cooling water passing through the heat exchanger was controlled using a solenoid valve. The cooled diesel was then returned to the tank.