Effect of fully blocked non-rigid boundary conditions on detonation wave

2018 ◽  
Vol 116 ◽  
pp. 52-60 ◽  
Author(s):  
Qingwei Guan ◽  
Wentao Ji ◽  
Xingqing Yan ◽  
Jianliang Yu ◽  
Futong Yao ◽  
...  
Keyword(s):  
Detonation Wave ◽  
Boundary Conditions ◽  
Rigid Boundary

scholarly journals Thermal detonation wave in liquid lead – water mixture

2021 ◽  
Vol 2088 (1) ◽  
pp. 012027
Author(s):  
A V Kapustin ◽  
V I Melikhov ◽  
O I Melikhov ◽  
B Saleh ◽  
D V Finoshkina
Keyword(s):  
Heat Transfer ◽  
Shock Wave ◽  
Detonation Wave ◽  
Boundary Conditions ◽  
Internal Structure ◽  
Interfacial Friction ◽  
Liquid Lead ◽  
Water Mixture ◽  
Friction Heat ◽  
Closing Relations

Abstract It was developed the model of thermal detonation in a mixture of continuous liquid lead and dispersed steam/water particles. Stationary equations of mass, impulse and energy conservations laws for multiphase continuum are applied to describe internal structure of thermal detonation wave. They are supplemented by closing relations describing interfacial friction, heat transfer, and fragmentation. Conditions at leading shock wave and at Chapman-Jouguet plane are used as boundary conditions.

Seismic Response Analysis of Twin-Tower Building with Enlarged Base

2014 ◽  
Vol 912-914 ◽  
pp. 1534-1537
Author(s):  
Shao Bo Zhang ◽  
Ke Lun Wei ◽  
Bi Jian Xiao
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Boundary Conditions ◽  
Seismic Response ◽  
Time History ◽  
Response Analysis ◽  
Rigid Boundary ◽  
Finite Element Software ◽  
Elastic Boundary ◽  
Elastic Boundary Conditions

This paper adopts large finite element software ANSYS to establish finite element model of twin-tower building with enlarged base, uses dynamic time history analysis method for seismic response calculation, compare and analyze the calculation results of twin-tower building with enlarged base under elastic boundary conditions and rigid boundary conditions. The results showe that dynamic response for model under elastic boundary conditions is larger than dynamic response for model under rigid boundary conditions, and elastic boundary conditions is more close to the actual situation.

Dislocation Dynamics Simulations

2012 ◽  
Vol 736 ◽  
pp. 13-20 ◽  
Author(s):  
Karri V. Mani Krishna ◽  
Prita Pant
Keyword(s):  
Boundary Conditions ◽  
Strain Hardening ◽  
Deformation Behaviour ◽  
Dislocation Dynamics ◽  
Clear Correlation ◽  
Rigid Boundary ◽  
Rate Of Increase ◽  
Dislocation Densities ◽  
Dynamics Simulations ◽  
Film Substrate

Dislocation Dynamics (DD) simulations are used to study the evolution of a pre-specified dislocation structure under applied stresses and imposed boundary conditions. These simulations can handle realistic dislocation densities ranging from 1010 to 1014 m-2, and hence can be used to model plastic deformation and strain hardening in metals. In this paper we introduce the basic concepts of DD simulations and then present results from simulations in thin copper films and in bulk zirconium. In both cases, the effect of orientation on deformation behaviour is investigated. For the thin film simulations, rigid boundary conditions are used at film-substrate and film-passivation interfaces leading to dislocation accumulation, while periodic boundaries are used for bulk grains of Zr. We show that there is a clear correlation between strain hardening rate and the rate of increase of dislocation density.

Patch Transfer Functions as a Tool to Couple Linear Acoustic Problems

2004 ◽  
Vol 127 (5) ◽  
pp. 458-466 ◽  
Author(s):  
Morvan Ouisse ◽  
Laurent Maxit ◽  
Christian Cacciolati ◽  
Jean-Louis Guyader
Keyword(s):  
Boundary Conditions ◽  
Strong Coupling ◽  
Transfer Functions ◽  
Acoustic Behavior ◽  
Rigid Boundary ◽  
Mean Values ◽  
Final Assembly ◽  
Coupling Case ◽  
Linear Problems ◽  
Basic Equations

A method to couple acoustic linear problems is presented in this paper. It allows one to consider several acoustic subsystems, coupled through surfaces divided in elementary areas called patches. These subsystems have to be studied independently with any available method, in order to build a database of transfer functions called patch transfer functions, which are defined using mean values on patches, and rigid boundary conditions on the coupling area. A final assembly, using continuity relations, leads to a very quick resolution of the problem. The basic equations are developed, and the acoustic behavior of a cavity separated in two parts is presented, in order to show the ability of the method to study a strong-coupling case. Optimal meshing size of the coupling area is then discussed, some comparisons with experiments are shown, and finally a complex automotive industrial case is presented.

scholarly journals Boundary conditions in problems of studying the stability of a plane stationary detonation wave

2017 ◽  
Author(s):  
A. S. Tytyapkin ◽  
V. E. Volkov
Keyword(s):  
Detonation Wave ◽  
Boundary Conditions ◽  
Shock Front ◽  
Continuous Distribution ◽  
Chemical Transformations ◽  
Explosion Safety ◽  
Gas Detonation ◽  
Explosion Protection ◽  
The Stability ◽  
Front Model

The research’s problems of a plane stationary detonation wave’s stability are considered. It is shown that the boundary conditions for the two-front model allow estimating the main parameters of the internal structure of gas detonation. Such a model can serve as the basis for development of mathematical support and software for an intellectual decision support system for the problems of explosion-proof and explosion protection. An attempt has been made to systematize the problem of setting boundary conditions in studies of the stability of a detonation wave in order to further create a decision support system (DSS) on problems of explosion safety and explosion protection. The following models of a plane stationary detonation wave were considered, which the stability problem is stated for: 1) the Chapman-Jouget detonation model is the simplest model where the shock-detonation front is modeled by a direct shock wave, and all chemical transformations are assumed to occur instantaneously, directly at the front; 2) a two-front (single-stage, square-wave) model based on the assumption that chemical transformations also occur instantaneously, not on the leading shock front, but in a plane (called the instantaneous combustion front), which is separated from the leading shock front by the induction zone; 3) a multistage model that approximates the continuous distribution of parameters behind the leading shock front piecewise constant function; 4) a model with a continuous distribution of parameters behind the leading shock front, which most accurately reflects the real physical processes in a stationary detonation wave. These models are fundamentally different in boundary conditions, which small pertur-bations in the region separating the regions of the initial combustible medium and detona-tion products satisfy. The advantages and disadvantages of the models described above are both assessed from the standpoint of the correctness of the physical analysis of the detonation process and from the point of view of applicability for the mathematical support of DSS on problems of explosion safety and explosion protection. It is shown that the boundary conditions for the two-front model allow to estimate the main parameters of the internal structure of the gas detonation. Such model can be as the basis for the development of mathematical support and software of DSS for problems of explosion safety and explosion protection

scholarly journals Inclined convection in a porous Brinkman layer: linear instability and nonlinear stability

2019 ◽  
Vol 475 (2223) ◽  
pp. 20180614 ◽  
Author(s):  
Paolo Falsaperla ◽  
Andrea Giacobbe ◽  
Giuseppe Mulone
Keyword(s):  
Boundary Conditions ◽  
Nonlinear Stability ◽  
Three Dimensional ◽  
Linear Instability ◽  
Nonlinear Analyses ◽  
Rigid Boundary ◽  
Link Type ◽  
Linear And Nonlinear ◽  
First Time ◽  
Stress Free Boundary

In this article, we deal with thermal convection in an inclined porous layer modelled by the Brinkman Law . Inertial effects are taken into account, and the physically significant rigid boundary conditions are imposed. This model is an extension of the work by Rees & Bassom (Rees & Bassom 2000 Acta Mech. 144 , 103–118 ( doi:10.1007/BF01181831 )), where Darcy's Law is adopted, and only linear instability is investigated. It also completes the work of Falsaperla & Mulone (Falsaperla & Mulone 2018 Ric. Mat. 144 , 1–17 ( doi:10.1007/s11587-018-0371-2 )), where the case of stress-free boundary conditions is studied and the inertial terms are absent. In this model, the basic laminar solution for the velocity is a combination of hyperbolic and polynomial functions, which makes the linear and nonlinear analysis much more complex. The original features of the paper are the following: we study three-dimensional perturbations , providing critical surfaces for the linear and nonlinear analyses; we study nonlinear stability with the Lyapunov method and, for the first time in the case of inclined layers, we compute the critical nonlinear Rayleigh regions by solving the associated variational maximum problem ; we give some estimates of global nonlinear asymptotical stability; we study linear instability and nonlinear stability also with the presence of the inertial term , i.e. for a finite Va.

Sediment deposit thickness and its effect on critical velocity for incipient motion

2016 ◽  
Vol 74 (8) ◽  
pp. 1876-1884 ◽  
Author(s):  
C. H. J. Bong ◽  
T. L. Lau ◽  
A. Ab. Ghani ◽  
N. W. Chan
Keyword(s):  
Boundary Conditions ◽  
Critical Velocity ◽  
Sediment Deposition ◽  
Incipient Motion ◽  
Rigid Boundary ◽  
Densimetric Froude Number ◽  
Deposit Thickness ◽  
Velocity Equation ◽  
Deposition Thickness ◽  
Sediment Deposit

The understanding of how the sediment deposit thickness influences the incipient motion characteristic is still lacking in the literature. Hence, the current study aims to determine the effect of sediment deposition thickness on the critical velocity for incipient motion. An incipient motion experiment was conducted in a rigid boundary rectangular flume of 0.6 m width with varying sediment deposition thickness. Findings from the experiment revealed that the densimetric Froude number has a logarithmic relationship with both the thickness ratios ts/d and ts/y0 (ts: sediment deposit thickness; d: grain size; y0: normal flow depth). Multiple linear regression analysis was performed using the data from the current study to develop a new critical velocity equation by incorporating thickness ratios into the equation. The new equation can be used to predict critical velocity for incipient motion for both loose and rigid boundary conditions. The new critical velocity equation is an attempt toward unifying the equations for both rigid and loose boundary conditions.

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