Analysis Of Physical Problems Research Articles

CompVision: An open-source five-compartmental software for biokinetic simulations

Abstract Simulations and numerical analysis of physical problems are important steps toward understanding underlying mechanisms of the processes. Important examples would be medical physics and medical imaging. Compartmental modeling has been found useful for estimating the transport and temporal variations of drugs/contaminants (commonly used in medical physics and medical imaging) in different organs, given that different organs would be modeled as compartments. Recycling among these modeled compartments (i.e., organs) was allowed through defining sets of constant transfer rates. In order to mathematically define these systems, one needs to use sets of differential equations (depending on the number of compartments) which would in fact be time-consuming and prone to mathematical error. Considering these issues, there is a need for a versatile computer program that is accurate, robust, and user-friendly to perform the required computations automatically. In the present work, we developed and benchmarked an open-source computer program entitled CompVision that was able to simulate five-compartmental systems. The present software had an easy-to-use graphical user interface (GUI) for the users. The executable program and the source codes were made available publicly under GPLv3 license, which would allow everyone to use, modify, and distribute without any restriction. The present program would be useful in a variety of research fields and applications.

Transient Free Convection Flow of a Micropolar Fluid Over a Vertical Surface

In recent years, the dynamics of micropolar fluids, originated from the theory of Eringen, has been a popular area of research. As the fluids consist of randomly oriented molecules, and as each volume element of the fluid has translational as well as rotational motions, the analysis of physical problems in these fluids has revealed several interesting phenomena, which are not found in Newtonian fluids. The present study presents a numerical study for transient natural convection heat transfer of a micropolar boundary layer flow near a vertical isothermal surface. The governing equations are formulated and solved numerically using the MackCormak’s technique. A comparison with previously published results on special cases of the problem shows excellent agreement. Representative results for the velocity, micro-rotation and temperature profiles are shown graphically for different values of material parameters. In general, it is found that the temperature increases inside the boundary layer for the micropolar flows as compared to the Newtonian flows.

Analytical studies on MHD oscillatory flow of a micropolar fluid over a vertical porous plate

In recent years, the dynamics of micropolar fluids, originated from the theory of Eringen (J. Math. Mech., 16 (1964) 1), has been a popular area of research. As the fluids consist of randomly oriented molecules, and as each volume element of the fluid has translation as well as rotation, the analysis of physical problems in these fluids has revealed several interesting phenomena, which are not found in Newtonian fluid. In this study, we investigate the problem of the oscillatory two-dimensional laminar flow of a viscous incompressible electrically conducting micropolar fluid over a semi-infinite vertical moving porous plate in the presence of a transverse magnetic field. Here, it is assumed that the size of holes in the porous plate is much larger than a characteristic microscopic length scale of the micropolar fluid to simplify formulation of the boundary conditions. The effects of various flow parameters and thermophysical properties on the flow and temperature fields across the boundary layer are investigated. Especially, the effects of non-zero values of micro-gyration vector on the velocity and temperature fields across the boundary layer are studied, using the method of small perturbation approximation. Numerical results of velocity profiles of micropolar fluids are compared with the corresponding flow problems for a Newtonian fluid. The results also show that there exists completely oscillating behavior in the velocity distribution.

Reliable non‐linear elastic constants

AbstractThe values given in the literature for the third‐order elastic constants cIJK of the standard semiconductors have long been suspect. We have applied modern statistical analysis to the raw data from which the databook cIJK were obtained, and we give revised values with reliable error estimates for Si, Ge and GaAs. The databook cIJK are appropriate for an expansion of the elastic energy of a body as a Taylor series in Lagrangian strain ηIJ, but there are formidable mathematical difficulties in using Lagrangian strain in the analysis of physical problems. To facilitate such analysis, we introduce effective second‐order elastic constants for materials under finite strain. From these, strain, stress and pressure derivatives are readily calculated. The pressure derivatives are given for Si, Ge and GaAs. Using the stress derivatives, the relationships between physical observables such as acoustic velocities and the databook cIJK can be obtained by simple algebra.

Qualitative Analysis of Physical Problems

M Gitterman and V Halpern 1981 London: Academic xiv + 274 pp price £13.80 This postgraduate book is organised around five qualitative methods used in the analysis of physical problems. Physical ideas from a wide variety of fields are continually introduced to illustrate the methods at work.