perturbation technique
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2022 ◽  
Vol 18 ◽  
Author(s):  
Maria Yasin ◽  
Sadia Hina ◽  
Rahila Naz ◽  
Thabet Abdeljawad ◽  
Muhammad Sohail

Aims:: This article is intended to investigate and determine combined impact of Slip and Hall current on Peristaltic transmission of Magneto-hydrodynamic (MHD) Eyring-Powell fluid. Background: The hall term arises taking strong force-field under consideration. Velocity, thermal and concentration slip conditions are applied. Energy equation is modeled by considering Joule-thermal effect. To observe non-Newtonian behavior of fluid the constitutive equations of Eyring-Powell fluid is encountered. Objective: Flow is studied in a wave frame of reference travelling with velocity of wave. The mathematical modeling is done by utilizing adequate assumptions of long wavelength and low Reynolds number. Method: The closed form solution for momentum, temperature and concentration distribution is computed analytically by using regular perturbation technique for small fluid parameter(A). Results: Graphical results are presented and discussed in detail to analyze behavior of sundry parameters on flow quantities (i.e. velocity, temperature and concentration profile). It is noticed that Powell-Eyring fluid parameters (A,B) have a significant role on the outcomes. Conclusion: The fluid parameter A magnifies the velocity profile whereas, the other fluid parameter B shows the opposite behavior.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Shubhra Bhowmick ◽  
Nabakumar Ghosh ◽  
Biswajit Sahu

Abstract A theoretical investigation has been carried out to explore the modulational instability (MI) of electrostatic waves in a warm multi-ion dusty plasma system containing positive ions, negative ions and positively or negatively charged dust in presence of superthermal electrons. With the help of the standard perturbation technique, it is found that the dynamics of the modulated wave is governed by a damped nonlinear Schrödinger equation (NLSE). Regions of MI of the electrostatic wave are precisely determined and the analytical solutions predict the formation of dissipative bright and dark solitons as well as dissipative first- and second-order rogue wave solutions. It is found that the striking features (viz., instability criteria, amplitude and width of rogue waves, etc.) are significantly modified by the effects of relevant plasma parameters such as degree of the electron superthermality, dust density, etc. The time dependent numerical simulations of the damped NLSE reveal that modulated electrostatic waves exhibit breather like structures. Moreover, phase plane analysis has been performed to study the dynamical behaviors of NLSE by using the theory of dynamical system. It is remarked that outcome of present study may provide physical insight into understanding the generation of several types of nonlinear structures in dusty plasma environments, where superthermal electrons, positive and negative ions are accountable (e.g. Saturn’s magnetosphere, auroral zone, etc.).


Author(s):  
Latif Ahmad ◽  
Saleem Javed ◽  
Muhammad Ijaz Khan ◽  
M. Riaz Khan ◽  
Essam Roshdy El-Zahar ◽  
...  

Particular non-axisymmetric Homann stagnation point flow of Walter’s B fluid over a vertical cylindrical disk is considered in this work. Important physical aspects of newly transient state problem are described by incorporating the effects of magnetic field and mixed convection. Additionally, the temperature and solute concentration are expressed with new parameters in the form of Brownian motion, thermophoretic force, thermal radiation, and 1st order chemical reaction. Furthermore, the problem is modeled with non-linear PDE’s, and which are further converted into ODE’s along with the proposed geometric conditions. Exploration of new physical impacts are described in the form of velocity, temperature, concentration, and displacement thicknesses by applying numerical scheme. However, the momentum equation subjected to the insufficient boundary conditions converting us to apply perturbation technique to reduce the order of ODE accordingly. It is conducted that displacement thicknesses [Formula: see text] and [Formula: see text] tends to its asymptotic value, as [Formula: see text] On the other hand, the displacement thickness [Formula: see text] is found in reverse trends, for the same escalating values of viscoelastic parameter. The skin friction [Formula: see text] variation against viscoelastic parameter is noticed with uplifting trend when [Formula: see text] and vice versa, for [Formula: see text] Outcomes for the Nusselt and Sherwood numbers and rate of heat and mass transfer have been obtained and discussed for parametric variations of the buoyancy parameter ξ, magnetic parameter M, temperature ratio parameter, Brownian motion parameter [Formula: see text], thermophoresis parameter [Formula: see text] and 1st order chemical reaction Rc. Also, shows relative growth for the momentum and concentration profiles.


2021 ◽  
Vol 35 (6) ◽  
pp. 447-456
Author(s):  
Preet Kamal Kaur ◽  
Kanwal Preet Singh Attwal ◽  
Harmandeep Singh

With the continuous advancements in Information and Communication Technology, healthcare data is stored in the electronic forms and accessed remotely according to the requirements. However, there is a negative impact like unauthorized access, misuse, stealing of the data, which violates the privacy concern of patients. Sensitive information, if not protected, can become the basis for linkage attacks. Paper proposes an improved Privacy-Preserving Data Classification System for Chronic Kidney Disease dataset. Focus of the work is to predict the disease of patients’ while preventing the privacy breach of their sensitive information. To accomplish this goal, a metaheuristic Firefly Optimization Algorithm (FOA) is deployed for random noise generation (instead of fixed noise) and this noise is added to the least significant bits of sensitive data. Then, random forest classifier is applied on both original and perturbed dataset to predict the disease. Even after perturbation, technique preserves required significance of prediction results by maintaining the balance between utility and security of data. In order to validate the results, proposed method is compared with the existing technology on the basis of various evaluation parameters. Results show that proposed technique is suitable for healthcare applications where both privacy protection and accurate prediction are necessary conditions.


Author(s):  
armand wirgin

This investigation is concerned with the 2D acoustic scattering problem of a plane wave propagating in a non-lossy, isotropic, homogeneous fluid host and soliciting a linear, isotropic, macroscopically-homogeneous, generally-lossy, flat-plane layer in which the mass density and wavespeed are different from those of the host. The focus is on the inverse problem of the retrieval of the layer mass density. The data is the transmitted pressure field, obtained by simulation (resolution of the forward problem) in exact, explicit form via the domain integral form of the Bergman wave equation. This solution is exact and more explicit in terms of the mass-density contrast (between the host and layer) than the classical solution obtained by separation of variables. A perturbation technique enables the solution (in its form obtained by the domain integral method) to be cast as a series of powers of the mass density contrast, the first three terms of which are employed as the trial models in the treatment of the inverse problem. The aptitude of these models to retrieve the mass density contrast is demonstrated both theoretically and numerically.


Author(s):  
M. Z. Bhatti ◽  
Z. Yousaf ◽  
M. Yousaf

This paper aims to investigate the stability constraints under the influence of particular modified gravity theory [Formula: see text], i.e. [Formula: see text] gravity in which the Lagrangian is a varying function of [Formula: see text] and trace of energy momentum tensor ([Formula: see text]). We examine stable behavior for compact cylindrical star having anisotropic symmetric configuration. We establish dynamical equations as well as equations of continuity in the background of this particular non-minimal coupled [Formula: see text]. We utilize perturbation technique which will be applied on geometrical as well as material physical quantities to constitute collapse equation. We continue this significant investigation to understand the dynamical behavior of considered cylindrical system under non-minimal coupled [Formula: see text] functional, i.e. [Formula: see text]. This gravitational function gives compatible findings only for [Formula: see text], also [Formula: see text] and [Formula: see text] considered in this astrophysical model as coupling entity. This model contains [Formula: see text] which is constant entity, having the values of order of the effective Ricci scalar [Formula: see text]. Furthermore, we impose some physical constraints to determine and maintain the stability criteria by establishing the expression of adiabatic index, i.e. [Formula: see text] for cylindrical anisotropic configuration, in Newtonian [Formula: see text] and post-Newtonian ([Formula: see text]) eras.


2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Huijing Zhan ◽  
Mingze Wu

In order to solve the numerical method of nonconservative ideal hydrodynamics equations, the viscous perturbation technique for solving nonconservative hydrodynamics equations is improved and tested by solving the Riemann problem. The calculation of nonconservative ideal fluid mechanics is based on the GRP format. This article aims at the calculation method of nonconservative ideal fluid mechanics in the GRP format. Riemann and the corresponding periodic vortex are processed. The multifluid network processing method in the article is compared with the current method. The result can prove that this format can be used to solve the nonconservative ideal fluid dynamics equation of multiple values in the GRP format group, its computing power is strong, and the result of the solution is accurate.


Author(s):  
Obulesu Mopuri ◽  
Charankumar Ganteda ◽  
Bhagyashree Mahanta ◽  
Giulio Lorenzini

The main aim of this investigation is to study thermo diffusion, heat source/sink, Joule and chemical effects on heat transfer in MHD mixed convection flow and mass transfer past an infinite vertical plate with ohmic heating and viscous dissipation have been studied. We consider the mixed convection flow of an incompressible and electrically conducting viscous fluid such that x* -axis is taken along the plate in upward direction and y* -axis is normal to it. A transverse constant magnetic field is applied i.e., in the direction of y*-axis. Approximate solutions have been derived for velocity, temperature, concentration profiles, skin friction, rate of heat transfer and rate of mass transfer using perturbation technique. The obtained results are discussed with the help of graphs to observe the effect of various parameters like Grashof number (Gr), the modified Grashof number (Gm), magnetic parameter (M), Permeability parameter(K), Prandtl number (Pr), Heat Sink(Q), Radiation Parameter (F), Soret parameter (S0), Eckert number (E),Schmidt number(Sc) and Chemical reaction parameter(K0) taking two cases viz. Fluid velocity, temperature and concentration profiles are comparison with Pr=0.71(Air) and Pr =7 (Water) various parameters in cooled and heated plates. Case I: when Gr > 0 (flow on cooled plate), and Case II: Gr < 0, (flow on heated plate). Both the fluid velocity and concentration rising with the increment values of Soret parameter in the fluids Air and Water and also discussed skin friction, Nusselt number and Sherwood number in the fluid’s mercury, electrolytic solution, air and water. The novelty of this study is the consideration of simultaneous occurrence of radiation, heat absorption as well as thermo- diffusion in the magnetic field. It varies in several aspects such as non-dimensional parameters, analytical solutions, and graphical solutions, the analytic solution using the Perturbation technique, and numerical solution using Matlab software for the profile.


Author(s):  
Mohammad Hojjati ◽  
Seyed Younes Farzanmehr ◽  
H. M. Navaz ◽  
Hassan Haddadpour

In this paper, a modified partial derivative method is developed to predict the linear and nonlinear dynamic coefficients of tilting-pad journal bearings with journal and pad perturbation. To this end, Reynolds equation and its boundary conditions along with equilibrium equations of the pad are used. Finite difference, partial derivative method, and perturbation technique have been employed simultaneously for solving these equations. The accuracy of the results is investigated by comparing the linear dynamic coefficients of three types of tilting-pad journal bearings with those published the literature. It is shown that the nonlinear dynamic coefficients depend on Sommerfeld number, eccentricity ratio, and length to diameter ratio. Similar to the case of linear dynamic coefficients of TPJB, it is observed that the eccentricity ratio effects on nonlinear dynamic coefficients are more notable when the eccentricity ratio is higher than 0.8 or less than 0.2.


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