Search

In this study, the Moore–Gibson–Thompson (MGT) concept of thermal conductivity is applied to a two-dimensional elastic solid in the form of a half-space. This model was constructed using Green and Naghdi's thermoelastic model to address the infinite velocity problem of heat waves. It has been taken into account that the free surface of the medium is immersed in an electromagnetic field of constant intensity, undergoes thermal shock, and rotates with a uniform angular velocity. The governing equations of a modified version of Ohm's law account for the impact of temperature gradients and charge densities. By using the method of normal mode analysis, an analytical representation of the studied physical fields was obtained. The effect of rotation and the modulus of modified Ohm's law on the responses of the field distributions examined is discussed, along with accompanying graphical representations. Other thermoelastic models have been compared with the results of the proposed system when the relaxation time is ignored. [ABSTRACT FROM AUTHOR]

Optical and photo-thermal effects have emerged in many fields, including thermal characterization, spectroscopy, transportation, and non-destructive examinations. In this study, the Moore-Gibson-Thompson (MGT) thermoelastic model is used to explore the photo-thermal coupling of an isotropic, homogeneous, semiconducting and thermomagnetic solid. The heat conduction law is modified to include the time derivative of fractional order and theoretically formulate the system of governing equations. Using the extended Mittag–Leffler functions as nonsingular kernels, the Atangana and Baleanu derivatives considers the features of fractional derivatives. As measured by an external reference frame, it is taken into account that the medium rotates with a constant angular velocity about the axis of symmetry. The cavity boundaries undergo thermal shock and time-varying heat flux. It has been shown that the Laplace transform method is a powerful technique for solving such problems that link the plasma and heat transfer with phase delays. It is finally aimed to describe the numerical results for changes in carrier density as a function of time and radial distance, temperature increment, strain, thermal stresses, and displacement using a photo-induced carrier with different values of physical relaxation time and fractional operator. [ABSTRACT FROM AUTHOR]

This work gives some results and develops the derivation of memory dependence heat conduction model with dual phase-lags using the modified definition of the fractional derivative of Caputo and higher-order memory-dependent derivative (MDD). The introduced model was derived by improving the heat conduction equation replacing the conventional Fourier's law and generalizing some of the previous models. As an application of the proposed model, we will consider an infinite thermoelastic long annular cylinder whose inner surface is thermally insulated and restricted, while the exterior surface is due to thermal shock and traction free. The numerical results of the physical fields are shown graphically against the position, and the effects of some basic parameters on them are estimated. Theoretical analysis and mathematical results confirm that the selection of an appropriate kernel, time delays and memory response can affect the turbulence in the thermal fields. [ABSTRACT FROM AUTHOR]

The main objective of this work is to study the homogeneous thermoelastic interactions in an isotropic hollow thin cylinder immersed in an electric–magnetic field using the linear Moore–Gibson–Thompson theory of thermoelasticity, taking into account the generalized Ohm's law. The MGT system of thermoelastic equations for the new model is created by incorporating a relaxation period in the Green–Naghdi type III framework. In addition, the Maxwell equations that investigate the effect of the electromagnetic field are presented. While the outer surface of the hollow cylinder is thermally insulated and free of traction, the interior surface is both free of traction and subject to thermal shock. To convert the problem to the space domain only, the Laplace transform methodology is used to solve the governing equations generated in the transformed domain. The theoretical results are computed dynamically and are graphically displayed for a transversely isotropic material using the Honig and Hirdes approach. A comparison of findings based on different (classical and generalized) thermoelastic theories is provided, followed by a discussion on the impact of the applied electromagnetic field. [ABSTRACT FROM AUTHOR]

In this work, we extend the modification of the generalized theories of thermoelasticity and photothermal. In this context, a new model has been derived based on the Moore-Gibson-Thompson (MGT) equation and combining the two models of thermoelasticity with one relaxation time (Lord-Shulman) and the theory of Green-Naghdi of the third type (GN-III). One of the most important features of the proposed model is that it predicts limited speeds of thermal signals and photovoltaic waves. The proposed model has been applied to examine the interactions between plasma, thermal, and elastic processes within a solid semiconductor sphere. It was taken into account that the sphere rotates with a constant angular velocity around its axis, is surrounded by an external magnetic field, and is also subjected to thermal shock. The singularities encountered in different physical fields have been addressed in the center and poles of the sphere. The influence of rotation and carrier lifetime parameters on different physical properties of semiconductor materials has been graphically displayed and explained using the Laplace method. [ABSTRACT FROM AUTHOR]

The present work is devoted to the derivation of fundamental equations in generalized thermoelastic diffusion with four lags and higher-order time-fractional derivatives. The equations of the heat conduction and the mass diffusion have been modified by using Taylor's series of time-fractional order. In this new model, the Fourier and the Fick laws have been modified to include a higher time-fractional order of the heat conduction vector, the gradient of temperature, the diffusing mass flux and the gradient of chemical potential. We adopted the definitions of Caputo and Jumarie; for time-fractional derivatives. The work of Nowacki; Sherief, Hamza, and Saleh; and Aouadi; are deduced as limit cases from the current investigation. Applying this formulation, we have discussed a thermoelastic-diffusion problem for a half-space exposed to thermal and chemical shock with a permeable material in contact with the half-surface. We discussed the sensitivity of the different physical parameters in all studied fields in detail and the results are presented graphically as well as in tabular forms. [ABSTRACT FROM AUTHOR]

Moore-Gibson-Thompson (MGT) is an equation which appropriately describes the spread of sound waves in gasses and fluids as well as thermal/mechanical waves in elastic bodies. The objective of this article is to theoretically analyze the generalized thermoelasticity models that have been presented as the development of the Fourier's law dealing with the paradox of unlimited propagation velocities of thermal waves. For this purpose, a new model is presented which combines the third type of Green and Naghdi model (GN-III) with the generalized theory including the relaxation time based on the MGT equation. The proposed model may be considered as a generalization of previous thermoelastic theories. To examine the introduced approach, the behavior of thermoelastic waves within a homogeneous isotropic sphere in which its surface is exposed to thermal shock with varying heat source is investigated. The variations in different physical fields of a given substance have been computed by means of Laplace transform technique and an efficient numerical technique is implemented in Laplace inversion procedure. The effect of different forms of heat source are also examined and several comparisons for various thermoelasticity approaches are comprehensively conducted. [ABSTRACT FROM AUTHOR]

Semiconductor materials, which are the aim of this study, are among the most recent advanced materials in the infrared and microwave domains. The reason for focusing on semiconducting elastic materials stems from their abundance in nature and also their numerous benefits in mechanical engineering and cotemporary physics. This work intends to provide a theoretical framework by considering the effects of thermal and electronic elastic deformation in a semiconductor medium during the exciting thermo-photovoltaic process. To this end, a modified photothermal model, in which the heat conduction is represented by the Moore–Gibson–Thompson (MGT) equation, is established by incorporating a relaxation parameter into the Green–Naghdi type III concept. The proposed model is used to investigate the interactions between plasma, thermal and elastic processes through a solid sphere of semiconductor material subject to a thermal shock in conjunction with an external magnetic field. The influence of thermal and carrier lifetime parameters on different physical properties of silicon material is graphically illustrated using theoretical simulated results by employing the Laplace technique. [ABSTRACT FROM AUTHOR]

Thermal and mass diffusion processes are important issues in a variety of engineering applications and scientific disciplines. The main objective of this research is to develop a new model that demonstrates diffusion in thermoelastic solids and compares the strain/temperature fields and mass diffusion. The proposed model is an extension of the Quintanilla model [1]. In the new model, Fourier's and Fick's laws have been improved by including the relaxation times in the Green–Naghdi theory in the framework of Moore–Gibson–Thompson (MGT) heat equation. Based on the introduced model, a one-dimensional half-space problem is considered. The surface surrounding the half-space is exposed to chemical potential and thermal shocks. Our findings indicate that the considered physical fields have a non-zero value only in a limited area and disappear outside this area. This result fully demonstrates the validity of the proposed model because the nature of velocities is limited by heat and diffusive waves. [ABSTRACT FROM AUTHOR]

The current study investigates thermophotovoltaic interactions using a new mathematical model of thermoelasticity established on a modification of the Green–Naghdi model of type III (GN-III). The basic equations, in which the heat transfer is in the form of the Moore–Gibson–Thompson (MGT) equation, are derived by adding a single delay factor to the GN-III model. The impact of temperature and electrical elastic displacement of semiconductors throughout the excited thermoelectric mechanism can be studied theoretically using this model. The proposed model was used to investigate the interactions between the processes of thermoelastic plasma in a rotating semiconductor solid sphere that was subjected to a thermal shock and crossed to an externally applied magnetic field. The influence of rotation parameters on various photothermal characteristics of silicon solid was presented and explored using the Laplace technique. [ABSTRACT FROM AUTHOR]