Application of a perturbation method to heat flow analysis in materials having temperature- dependent properties

AIAA Journal ◽  
1970 ◽  
Vol 8 (10) ◽  
pp. 1902-1903 ◽  
Author(s):  
ULF OLSSON
Keyword(s):  
Heat Flow ◽  
Perturbation Method ◽  
Flow Analysis ◽  
Temperature Dependent ◽  
Temperature Dependent Properties

Transient Thermoelastic Problem for an Infinite Medium With a Spherical Cavity Exhibiting Temperature-Dependent Properties

1962 ◽  
Vol 29 (2) ◽  
pp. 399-407 ◽  
Author(s):  
Jerzy Nowinski
Keyword(s):  
Thermal Expansion ◽  
Shear Modulus ◽  
Perturbation Method ◽  
Temperature Rise ◽  
Spherical Cavity ◽  
Infinite Medium ◽  
Thermoelastic Problem ◽  
Linear Variation ◽  
Temperature Dependent ◽  
Temperature Dependent Properties

This paper is concerned with a polarly symmetric transient thermoelastic problem for an infinite medium with a spherical cavity, the boundary of the cavity being subjected to a sudden temperature rise. Thermal and elastic properties of the medium are assumed to be temperature dependent. Using the perturbation method general equations for the displacements and stresses corresponding to particular boundary-value problems have been found. An illustrative example, involving linear variation of conductivity and thermal expansion as well as quadratic variation of shear modulus with temperature, has been discussed in detail.

scholarly journals Application of Perturbation Theory in Heat Flow Analysis

2021 ◽  
Author(s):  
Neelam Gupta ◽  
Neel Kanth
Keyword(s):  
Partial Differential Equations ◽  
Heat Flow ◽  
Differential Equations ◽  
Perturbation Method ◽  
Homotopy Perturbation Method ◽  
Perturbation Methods ◽  
Separation Of Variables ◽  
Flow Analysis ◽  
Partial Differential ◽  
Homotopy Perturbation

Many physical and engineering problems can be modeled using partial differential equations such as heat transfer through conduction process in steady and unsteady state. Perturbation methods are analytical approximation method to understand physical phenomena which depends on perturbation quantity. Homotopy perturbation method (HPM) was proposed by Ji Huan He. HPM is considered as effective method in solving partial differential equations. The solution obtained by HPM converges to exact solution, which are in the form of an infinite function series. Biazar and Eslami proposed new homotopy perturbation method (NHPM) in which construction of an appropriate homotopy equation and selection of appropriate initial approximation guess are two important steps. In present work, heat flow analysis has been done on a rod of length L and diffusivity α using HPM and NHPM. The solution obtained using different perturbation methods are compared with the solution obtained from most common analytical method separation of variables.

scholarly journals Temperature-Dependent Properties of Molten Li2BeF4 Salt Using Ab Initio Molecular Dynamics

ACS Omega ◽  
2021 ◽  
Author(s):  
Khagendra Baral ◽  
Saro San ◽  
Ridwan Sakidja ◽  
Adrien Couet ◽  
Kumar Sridharan ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Ab Initio ◽  
Ab Initio Molecular Dynamics ◽  
Temperature Dependent ◽  
Temperature Dependent Properties

Crystal structure and temperature-dependent properties of Na2H4Ga2GeO8 – a novel gallogermanate

2020 ◽  
Vol 75 (9-10) ◽  
pp. 805-813
Author(s):  
Irma Peschke ◽  
Lars Robben ◽  
Christof Köhler ◽  
Thomas Frauenheim ◽  
Josef-Christian Buhl ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Decomposition Temperature ◽  
Spectroscopic Techniques ◽  
Charge Balance ◽  
Temperature Dependent ◽  
Raman Spectroscopic ◽  
Debye Temperatures ◽  
Diffraction Lattice ◽  
Temperature Dependent Properties ◽  
Balance Structure

AbstractSynthesis, crystal structure and temperature-dependent behavior of Na2H4Ga2GeO8 are reported. This novel gallogermanate crystallizes in space group I41/acd with room-temperature powder diffraction lattice parameters of a = 1298.05(1) pm and c = 870.66(1) pm. The structure consists of MO4 (M = Ga, Ge) tetrahedra in four-ring chains, which are connected by two different (left- and right-handed) helical chains of NaO6 octahedra. Protons coordinating the oxygen atoms of the GaO4 tetrahedra not linked to germanium atoms ensure the charge balance. Structure solution and refinement are based on single crystal X-ray diffraction measurements. Proton positions are estimated using a combined approach of DFT calculations and NMR, FTIR and Raman spectroscopic techniques. The thermal expansion was examined in the range between T = 20(2) K and the compound’s decomposition temperature at 568(5) K, in which no phase transition could be observed, and Debye temperatures of 266(11) and 1566(65) K were determined for the volume expansion.

scholarly journals A new boundary element algorithm for modeling and simulation of nonlinear thermal stresses in micropolar FGA composites with temperature-dependent properties

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Mohamed Abdelsabour Fahmy
Keyword(s):  
Modeling And Simulation ◽  
Boundary Element ◽  
Thermal Stresses ◽  
Computation Time ◽  
Functionally Graded ◽  
Temperature Dependent ◽  
Time Step ◽  
Kirchhoff Transformation ◽  
Nonlinear Temperature ◽  
Temperature Dependent Properties

AbstractThe main aim of this article is to develop a new boundary element method (BEM) algorithm to model and simulate the nonlinear thermal stresses problems in micropolar functionally graded anisotropic (FGA) composites with temperature-dependent properties. Some inside points are chosen to treat the nonlinear terms and domain integrals. An integral formulation which is based on the use of Kirchhoff transformation is firstly used to simplify the transient heat conduction governing equation. Then, the residual nonlinear terms are carried out within the current formulation. The domain integrals can be effectively treated by applying the Cartesian transformation method (CTM). In the proposed BEM technique, the nonlinear temperature is computed on the boundary and some inside domain integral. Then, nonlinear displacement can be calculated at each time step. With the calculated temperature and displacement distributions, we can obtain the values of nonlinear thermal stresses. The efficiency of our proposed methodology has been improved by using the communication-avoiding versions of the Arnoldi (CA-Arnoldi) preconditioner for solving the resulting linear systems arising from the BEM to reduce the iterations number and computation time. The numerical outcomes establish the influence of temperature-dependent properties on the nonlinear temperature distribution, and investigate the effect of the functionally graded parameter on the nonlinear displacements and thermal stresses, through the micropolar FGA composites with temperature-dependent properties. These numerical outcomes also confirm the validity, precision and effectiveness of the proposed modeling and simulation methodology.

scholarly journals Time dependent and temperature dependent properties of the forward voltage characteristic of InGaN high power LEDs

AIP Advances ◽  
2017 ◽  
Vol 7 (3) ◽  
pp. 035206
Author(s):  
P. L. Fulmek ◽  
P. Haumer ◽  
F. P. Wenzl ◽  
W. Nemitz ◽  
J. Nicolics
Keyword(s):  
High Power ◽  
Voltage Characteristic ◽  
Time Dependent ◽  
Temperature Dependent ◽  
Forward Voltage ◽  
Temperature Dependent Properties
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