Study on Pounding Response of Adjacent Inelastic SDOF Structures Based on Dimensional Analysis

The dimensional analysis method is applied to study the pounding response of two inelastic single-degree-of-freedom (SDOF) structures under simplified earthquake excitation. The improved Kelvin pounding model is used to simulate the force and deformation of the collider during the contact process. Using bilinear interstory resistance model to simulate the inelastic characteristics of SDOF structures, the expression of dimensionless pounding force and the dimensionless equation of motion during the pounding process are deduced. When dimensionless parameters are used to represent the colliding equation of adjacent inelastic SDOF structures, the variables affecting the pounding response of the adjacent structures are reduced from 14 to 11, which can clearly reflect the rules during the pounding process. The correctness and superiority of the improved Kelvin model are verified by comparing the pounding responses between the improved Kelvin model and Kelvin model. The pounding response of the two inelastic SDOF structures with improved Kelvin model is illustrated in the form of spectra, and the self-similarity of pounding response of the two inelastic SDOF structures is revealed. The effects of structural parameters on the pounding response are analyzed. The results show that the effects of mass ratio, frequency ratio, and initial spacing between the adjacent inelastic SDOF structures on the pounding response of the left-side structure (with smaller mass and stiffness) are closely related to the division of spectral regions. For the right-side structure with larger mass and stiffness, the amplification of pounding on structural response increases with the increase of mass ratio Π m and decreases with the increase of frequency ratio μ and structural spacing Π d .

Influence Of Rotation, Variable Viscosity And Temperature On Peristaltic Transport In An Asymmetric Channel

In this paper we investigates the effects of each rotation, variable viscosity and temperature on the peristaltic phenomena in an asymmetric channel. The motion and heat equations are obtained in Cartesian coordinates, the dimensionless form of the governing equation are controlled by many dimensionless number e.g. Reynolds, Hartmann, Grashof , Prandle …These equations are nonlinear and to simplify ,the long wave length and low Reynolds number is used. The resulting dimensionless equation are then solved analytically by using perturbation expansion about Reynold model viscosity number. The effects of different parameter on axial velocity, stream function, pressure rise and heat distribution are analysis graphically by using the mathematica package.

Analytical solution and numerical simulation of the thermal entrance region problem for laminar flow through a circular pipe

In this paper, the assumptions implicited in Leveque’s approximation are re-examined, and the variation of the temperature and the thickness of the boundary layer were illustrated using the developed solution. By defining a similarity variable, the governing equations are reduced to a dimensionless equation with an analytic solution in the entrance region. This report gives justification for the similarity variable via scaling analysis, details the process of converting to a similarity form, and presents a similarity solution. The analytical solutions are then checked against numerical solution programming by FORTRAN code obtained via using Runge–Kutta fourth order (RK4) method. Finally, other important thermal results obtained from this analysis, such as; approximate Nusselt number in the thermal entrance region was discussed in detail. A comparison with the previous study available in literature has been done and found an excellent agreement with the published data.

Experimental study on influence of molding parameters on self-reinforcement characteristics of polymer co-injection molding

In this paper, self-reinforced samples with different mechanical properties were obtained by adjusting the molding parameters by co-injection molding technology, and the micro-morphology of these samples was observed. Then, using structured statistical methods, the analysis of variance and response surface methodology were used to study the effects of various molding variables on the morphology and properties of the materials, and to determine the most important molding variables and their interaction relationships. Finally, the associated experimental data were fitted by the least square minimization program, and the parameters in the fitting equation were dimensionless to obtain the correlative dimensionless equation. The purpose was to establish the mechanism model of the influence of the molding parameters on the co-injection self-reinforced sample and to objectively analyze its mechanism. It was found that the melt temperature is the most important factor affecting the morphology and mechanical properties. The highly oriented skin thickness is the most important factor in determining the tensile properties of the sample. The change in crystallinity is the most important factor in relation to the elastic modulus. Through the establishment of the relevant dimensionless equations, the theoretical study on the tensile strength and elastic modulus of the co-injection self-reinforced samples of the molding parameters was preliminarily realized.

The Correction of the Dimensionless Equation for the Mass Transfer Coefficient Estimation during the Membrane Modules Regeneration

The cleaning or regeneration of fouled membrane modules is an essential procedure in the membrane equipment operation. Despite the development of some successful cleaning techniques, the predictions of the membrane separation process operation parameters after regeneration is still an unsolved problem. In our previous works, the attempt to develop the methodology of estimating the membrane productivity after the regeneration of the fouled spiral wound membrane modules by cleaning the subatmospheric pressure has been made. However, this methodology requires some improvement, including the correction of the dimensionless equation to calculate the mass transfer coefficient. In this work, a set of additional experiments was carried out, and the corrections of the mass transfer correlation were done using both new and previously obtained experimental data. As a result, the improved dimensionless equation was contained as Sh = 0.00045Re0.8Sc0.33(de/l). This equation is valid in the range of Reynolds number variation of 0.4–60.0 for the case of the regeneration of spiral wound modules and can be used for the prediction of the permeate flux after the regeneration procedure.

Analytical solution and numerical approaches of the generalized Levèque equation to predict the thermal boundary layer

In this paper, the assumptions implicit in Leveque's approximation are re-examined, and the variation of the temperature and the thickness of the boundary layer were illustrated using the developed solution. By defining a similarity variable the governing equations are reduced to a dimensionless equation with an analytic solution in the entrance region. This report gives justification for the similarity variable via scaling analysis, details the process of converting to a similarity form, and presents a similarity solution. The analytical solutions are then checked against numerical solution programming by FORTRAN code obtained via using Runge-Kutta fourth order (RK4) method. Finally, others important thermal results obtained from this analysis, such as; approximate Nusselt number in the thermal entrance region was discussed in detail.

Transport phenomena of fire-induced smoke flow in a semi-open vertical shaft

PurposeThe purpose of this study is to investigate the transport phenomena of smoke flow in a semi-open vertical shaft.Design/methodology/approachThe large eddy simulation (LES) method was used to model the movement of fire-induced thermal flow in a full-scale vertical shaft. With this model, different fire locations and heat release rates (HRRs) were considered simultaneously.FindingsIt was determined that the burning intensity of the fire is enhanced when the fire attaches to the sidewall, resulting in a larger continuous flame region in the compartment and higher temperatures of the spill plume in the shaft compared to a center fire. In the initial stage of the fire with a small HRR, the buoyancy-driven spill plumes incline toward the side of the shaft opposite the window. Meanwhile, the thermal plumes are also directed away from the center of the shaft by the entrained airflow, but the inclination diminishes as HRR increases. This is because a greater HRR produces higher temperatures, resulting in a stronger buoyancy to drive smoke movement evenly in the shaft. In addition, a dimensionless equation was proposed to predict the rise-time of the smoke plume front in the shaft.Research limitations/implicationsThe results need to be verified with experiments.Practical implicationsThe results could be applied for design and assessment of semi-open shafts.Originality/valueThis study shows the transport phenomena of smoke flow in a vertical shaft with one open side.

A Modified HLD-NAC Equation of State To Predict Alkali/Surfactant/Oil/Brine Phase Behavior

Summary Reservoir crudes often contain acidic components (primarily naphthenic acids), which undergo neutralization to form soaps in the presence of alkali. The generated soaps perform synergistically with injected synthetic surfactants to mobilize waterflood residual oil in what is termed alkali/surfactant/polymer (ASP) flooding. The two main advantages of using alkali in enhanced oil recovery (EOR) are to lower cost by injecting a lesser amount of expensive synthetic surfactant and to reduce adsorption of the surfactant on the mineral surfaces. The addition of alkali, however, complicates the measurement and prediction of the microemulsion phase behavior that forms with acidic crudes. For a robust chemical-flood design, a comprehensive understanding of the microemulsion phase behavior in such processes is critical. Chemical-flooding simulators currently use Hand's method to fit a limited amount of measured data, but that approach likely does not adequately predict the phase behavior outside the range of the measured data. In this paper, we present a novel and practical alternative. In this paper, we extend a dimensionless equation of state (EOS) (Ghosh and Johns 2016b) to model ASP phase behavior for potential use in reservoir simulators. We use an empirical equation to calculate the acid-distribution coefficient from the molecular structure of the soap. Key phase-behavior parameters such as optimum salinities and optimum solubilization ratios are calculated from soap-mole-fraction-weighted equations. The model is tuned to data from phase-behavior experiments with real crudes to demonstrate the procedure. We also examine the ability of the new model to predict fish plots and activity charts that show the evolution of the three-phase region. The predictions of the model are in good agreement with measured data.

On the modified Reynolds equation for journal bearings in a case of non-Newtonian Rabinowitsch fluid model

In this paper, a theoretical analysis of hydrodynamic plain journal bearings with finite length at taking into account the effect of non-Newtonian lubricants is presented. Based upon the Rabinowitsch fluid model (cubic stress constitutive equation) and by integrating the continuity equation across the film, the nonlinear modified 2D Reynolds type equation is derived in details so that to study the dilatant and pseudoplastic nature of the lubricant in comparison with Newtonian fluid. A dimensionless equation of hydrodynamic pressure distribution in a form appropriate for numerical modeling is also presented. Some particular cases of 1D applications can be recovered from the present derivation.

Pemodelan Matematika Perpindahan Panas Konveksi Campuran (Mixed Convection) pada Pelat Horizontal

This study examines and analyzes mathematical model of mixed convection in horizontal plate. The heat transfer uses the model of a two dimensional nonlinear partial differential equations system. Then, this equation is derived first into the dimensionless equation form, and then it is changed into system of nonlinear ordinary differential equations form using similarity transformation. This system of nonlinear ordinary differential equations is solved by using the finite-difference scheme method, also with the mathematics program with software Matlab. The results obtained form this program is to determine skin friction coefficient , wall temperature velocity profiles and temperature profiles