Explicit-Implicit Schemes for Calculating the Dynamics of Layered Media with Nonlinear Conditions at Contact Boundaries

In this paper we consider the problem of dynamic loading of a deformable solid medium con- taining slip planes with nonlinear slip conditions on them. An explicit-implicit scheme was constructed for the numerical solution of the constitutive system of equations, which exactly reduces to correcting the stress tensor values after performing the elastic step. An implicit approximation of the constitutive relations containing a small parameter in the denominator of the nonlinear free term was used with the second order of the approximation. The correction procedure is applicable for those cases when the viscosity parameter of interlayers providing the sliding mode of the contact boundaries is not small. The solution of the problem of the seismic waves propagation in an inhomogeneous fractured geological massif in a two-dimensional case was obtained numerically

The Viscosity Parameter for Late-type Stable Be Stars

Using hydrodynamic principles we investigate the nature of the disk viscosity following the parameterization by Shakura & Sunyaev adopted for the viscous decretion model in classical Be stars. We consider a radial viscosity distribution including a constant value, a radially variable α assuming a power-law density distribution, and isothermal disks, for a late-B central star. We also extend our analysis by determining a self-consistent temperature disk distribution to model the late-type Be star 1 Delphini, which is thought to have a nonvariable, stable disk as evidenced by Hα emission profiles that have remained relatively unchanged for decades. Using standard angular momentum loss rates given by Granada et al., we find values of α of approximately 0.3. Adopting lower values of angular momentum loss rates, i.e., smaller mass loss rates, leads to smaller values of α. The values for α vary smoothly over the Hα emitting region and exhibit the biggest variations nearest the central star within about five stellar radii for the late-type, stable Be stars.

FE Modelling and Analysis of Beam Column Joint Using Reactive Powder Concrete

Reactive powder concrete (RPC) is used in the beam-column joint region in two out of four frames. Finite element modeling of all specimens is developed by using ABAQUS software. Displacement controlled analysis is used rather than load control analysis to obtain the actual response of the structure. The prepared models were verified by using experimental results. The results showed that using RPC in the joint region increased the overall strength of the structure by more than 10%. Moreover, it also helped in controlling the crack width. Furthermore, using RPC in the joint region increased the ductility of the structures. Comparisons were made by varying the size of the mesh and viscosity parameter values. It was found that by increasing the mesh size and viscosity parameter value, analysis time and the number of steps during analysis were reduced. This study provides a new modeling approach using RPC beam-column joint to predict the behavior and response of structures and to improve the shear strength deformation against different structural loading.

RK4 and HAM Solutions of Eyring–Powell Fluid Coating Material with Temperature-Dependent-Viscosity Impact of Porous Matrix on Wire Coating Filled in Coating Die: Cylindrical Co-Ordinates

In this work, we studied the impacts of transmitting light, nonlinear thermal, and micropolar fluid mechanics on a wire surface coating utilizing non-Newtonian viscoelastic flow. Models with temperature-dependent variable viscosity were used. The boundary layer equations governing the flow and heat transport processes were solved using the Runge–Kutta fourth order method. A distinguished constituent of this study was the use of a porous matrix that acted as an insulator to reduce heat loss. In this paper we discuss the effects of numerous development parameters, including β0, Q, m, Ω, Kp, and Br (non-Newtonian parameter, heat-producing parameter, viscosity parameter, variable viscosity parameter, porosity parameter, and Brinkman number, respectively). Furthermore, the effects of two other parameters, D and M, are also discussed as they relate to velocity and temperature distributions. We observed that the velocity profiles decreased with increasing values of Kp. Fluid velocity increased as the values of M, Br, N, and D increased, while it decreased when the values of Kp, Q, and D increased. For increasing values of M, the temperature profile showed increasing behavior, while Br and Q showed decreasing behavior. Furthermore, the present work is validated by comparison with HAM and previously published work, with good results.

Unsteady flow of three-dimensional Maxwell nanofluid with variables properties over a stretching surface

The present article focuses on the time-dependent three-dimensional Maxwell fluid flow with temperature-dependent fluid properties along the stretching sheet. The heat and mass transfer analysis are presented in the occurrence of activation energy, convective boundary condition, and non-uniform heat source/sink effect. The flow model is converted into a system of coupled ODEs with the help of a similarity transformation. The numerical built-in technique Bvp4c is employed to solve the obtained coupled ODEs. The graphical outcomes are obtained against the various parameters and discussed. It is seen from the graphs that fluid velocity diminishes for stronger values of relaxation parameter and shows an opposite trend for the variable viscosity parameter. Moreover, it is noted from the tabulated data that the heat and mass transfer rate reduces for the stronger values of unsteadiness and the variable viscosity parameter.

An assessment of the mathematical model for estimating of entropy optimized viscous fluid flow towards a rotating cone surface

Entropy optimization in convective viscous fluids flow due to a rotating cone is explored. Heat expression with heat source/sink and dissipation is considered. Irreversibility with binary chemical reaction is also deliberated. Nonlinear system is reduced to ODEs by suitable variables. Newton built in shooting procedure is adopted for numerical solution. Salient features velocity filed, Bejan number, entropy rate, concentration and temperature are deliberated. Numerical outcomes for velocity gradient and mass and heat transfer rates are displayed through tables. Assessments between the current and previous published outcomes are in an excellent agreement. It is noted that velocity and temperature show contrasting behavior for larger variable viscosity parameter. Entropy rate and Bejan number have reverse effect against viscosity variable. For rising values of thermal conductivity variable both Bejan number and entropy optimization have similar effect.

Modeling Heat Transfer Enhancement of Ferrofluid (Fe3O4–H2O) Flow in a Microchannel Filled with a Porous Medium

Heat transfer characteristics and hydrodynamical properties of ferrofluid through microchannels with non-uniform permeable walls temperature and filled with porous media plays an important role in modern microfluidic applications, such as solar collectors, nuclear reactors, micro-electro-chemical cell transport, micro heat exchanging, microchip cooling, and electronic equipment. Therefore, this paper presents the investigation of ferrofluid (Fe3O4-H2O) heat transfer characteristics as well as hydrodynamical properties in a permeable microchannel with non-uniform permeable walls. The semi-discretization finite difference method is utilized to solve the highly non-linear partial differential equations that govern the momentum and energy equations. Accordingly, the numerical outcomes reveal that the ferrofluid velocity and temperature profiles indicate a rising trend as the pressure gradient parameter, the variable viscosity parameter, the Darcy number, the Eckert number, and Prandtl number increase. The Reynolds number, which is a suction/injection parameter, shows a contrary influence on the ferrofluid velocity and temperature whereas nanoparticles volume fraction and the Forchheimer constant show a decreasing effect on the ferrofluid velocity and temperature. The outcomes also depict that the coefficient of skin friction at the cold wall of the microchannel is larger for higher values of the nanoparticles volume fraction, the variable viscosity parameter, the Darcy number, and the Eckert number. Besides, the coefficient of skin friction at the hot wall rises with the Darcy number, and the Prandtl number. Furthermore, the heat transfer rate at both cold and hot walls of the microchannel increases as the variable viscosity parameter, the Darcy number, the Eckert number, and the Prandtl number increase. The nanoparticles volume fraction and Darcy number show a retarding effect on the heat transfer rate at both walls of the microchannel.

Investigation of variable viscosity and thermal conductivity on MHD mass transfer flow problem over a moving non-isothermal vertical plate

In this paper we investigate numerically the influence of variable viscosity and thermal conductivity on MHD convective flow of heat and mass transfer problem over a moving non-isothermal vertical plate. The viscosity of the fluid and thermal conductivity are presumed to be the inverse linear functions of temperature. With the help of similarity substitution, the flow governing equations and boundary conditions are transformed into non-dimensional ordinary differential equations. The boundary value problem so obtained is then solved using MATLAB bvp4c solver. The effects of various parameters viz. magnetic parameter, viscosity parameter, thermal conductivity parameter, stratification parameter and Schmidt number on velocity, temperature and concentration are obtained numerically and presented trough graphs. Also the coefficient of skin-friction, Nusselt number and Sherwood number are computed and displayed in tabular form. The effects of the viscosity parameter and thermal conductivity parameter in particular are prominent. This study has applications in a number of technological processes such as metal and polymer extrusion.

MHD squeezed Darcy–Forchheimer nanofluid flow between two h–distance apart horizontal plates

This research is mainly concerned with the characteristics of magnetohydrodynamics and Darcy–Forchheimer medium in nanofluid flow between two horizontal plates. A uniformly induced magnetic impact is involved at the direction normal to the lower plate. Darcy–Forchheimer medium is considered between the plates that allow the flow along horizontal axis with additional effects of porosity and friction. The features of Brownian diffusive motion and thermophoresis are disclosed. Governing problems are transformed into nonlinear ordinary problems using appropriate transformations. Numerical Runge–Kutta procedure is applied using MATLAB to solve the problems and acquire the data for velocity field, thermal distribution, and concentration distribution. Results have been plotted graphically. The outcomes indicate that higher viscosity results in decline in fluid flow. Thermal profile receives a decline for larger viscosity parameter; however, Brownian diffusion and thermophoresis appeared as enhancing factors for the said profile. Numerical data indicate that heat flux reduces for viscosity parameter. However, enhancement is observed in skin-friction for elevated values of porosity factor. Data of this paper are practically helpful in industrial and engineering applications of nanofluids.

Modeling dynamic spherical cavity expansion in elasto-viscoplastic media

In this paper, we extend the dynamic spherical cavity expansion model for rate-independent materials developedin refs. [1, 2, 3] to viscoplastic media. For that purpose, we describe the material behavior with an isotropic Perzyna-type overstress formulation [4, 5] in which the material rate-dependence is controlled by the viscosity parameter\eta. The theoretical predictions of the cavity expansion model, which assumes that the cavity expands at constantvelocity, are compared with finite element simulations performed in ABAQUS/Explicit [6]. The agreement betweentheory and numerical simulations is excellent for the whole range of cavitation velocities investigated, and for different values of the parameter \eta. We show that, as opposed to the steady-state self-similar solutions obtained for rate-independent materials [1, 2, 3], the material viscosity leads to time-dependent cavitation fields and stress relaxation as the cavity enlarges. In addition, we also show that the material viscosity facilitates to model the shock waves that emerge at the highest cavitation velocities investigated, controlling the amplitude and the width of the shock front.