Constructal Placement of High-Conductivity Inserts in a Slab: Optimal Design of “Roughness”

2001 ◽  
Vol 123 (6) ◽  
pp. 1184-1189 ◽  
Author(s):  
M. Neagu and ◽  
A. Bejan
Keyword(s):  
Numerical Simulation ◽  
Heat Conduction ◽  
Optimal Design ◽  
Contact Resistance ◽  
Rough Surface ◽  
Fundamental Problem ◽  
Three Dimensional ◽  
High Conductivity ◽  
Constant Thickness ◽  
Two Dimensional

This paper addresses the fundamental problem of how to facilitate the flow of heat across a conducting slab heated from one side. Available for distribution through the system is a small amount of high-conductivity material. The constructal method consists of optimizing geometrically the distribution of the high-conductivity material through the material of lower conductivity. Two-dimensional distributions (plate inserts) and three-dimensional distributions (pin inserts) are optimized based on the numerical simulation of heat conduction in a large number of possible configurations. Results are presented for the external and internal features of the optimized architectures: spacings between inserts, penetration distances, tapered inserts and constant-thickness inserts. The use of optimized pin inserts leads consistently to lower global thermal resistances than the use of plate inserts. The side of the slab that is connected to the high-conductivity intrusions is in effect a “rough” surface. This paper shows that the architecture of a rough surface can be optimized for minimum global contact resistance. Roughness can be designed.

Application and Research of Digital Technology in Optimal Design of CNC Floor Boring and Milling Machine

2012 ◽  
Vol 429 ◽  
pp. 111-115
Author(s):  
Zhen Long Leng ◽  
Jin Feng Yang ◽  
Qun Ping Liu ◽  
Xun Deng
Keyword(s):  
Numerical Simulation ◽  
Optimal Design ◽  
Digital Technology ◽  
Three Dimensional ◽  
Milling Machine ◽  
Machine Model ◽  
Digital Modeling ◽  
Key Technologies ◽  
The Cost ◽  
Interference Checking

This paper focuses on application of the three-dimensional digital modeling, numerical analysis and optimization, digital control and other key technologies which provide technical support for the design and development in CNC floor boring and milling machine manufactruing. The three-dimensional digital modeling, digital assembly, interference checking help to eliminate some hidden trouble before processing and assembly. Numerical simulation reduces the cost and shortens the cycle of designand manufactruing in the optimal design of the machine. This technique has been successfully applied to a CNC Floor Boring and Milling Machine Model, which has been running for three years and achieved satisfactary economic result.

scholarly journals Modelling of the processes of impact of a projectile with elements of individual defence

2019 ◽  
Vol 221 ◽  
pp. 01021
Author(s):  
Aleksandr Kraus ◽  
Evgeny Kraus ◽  
Ivan Shabalin
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Heterogeneous Media ◽  
Three Dimensional ◽  
Stationary Problem ◽  
Heterogeneous Structure ◽  
Plate Steel ◽  
Two Dimensional ◽  
Human Bones ◽  
Armor Plate

A two-dimensional and three-dimensional non-stationary problem of the interaction of a homogeneous impactor and a heterogeneous structure made of steel and ceramics and placed in a Kevlar pocket is considered. The model of the human body is a plate of gelatine with cylindrical inserts-imitators of human bones. The results of numerical simulation using different approaches for describing heterogeneous media are compared. On the basis of direct numerical simulation, it is shown that the gradient armor plate (steel + B4C) has the best weight and size parameters.

Symbolic computation study on exact solutions to a generalized (3+1)-dimensional Kadomtsev-Petviashvili-type equation

2020 ◽  
pp. 2150116
Author(s):  
Cheng-Cheng Zhou ◽  
Xing Lü ◽  
Hai-Tao Xu
Keyword(s):  
Numerical Simulation ◽  
Exact Solutions ◽  
Prime Number ◽  
Symbolic Computation ◽  
Three Dimensional ◽  
Type Equation ◽  
Two Dimensional ◽  
Type Solution ◽  
Bilinear Operators ◽  
Number Formula

Based on the prime number [Formula: see text], a generalized (3+1)-dimensional Kadomtsev-Petviashvili (KP)-type equation is proposed, where the bilinear operators are redefined through introducing some prime number. Computerized symbolic computation provides a powerful tool to solve the generalized (3+1)-dimensional KP-type equation, and some exact solutions are obtained including lump-type solution and interaction solution. With numerical simulation, three-dimensional plots, density plots, and two-dimensional curves are given for particular choices of the involved parameters in the solutions to show the evolutionary characteristics.

Numerical Simulation of Thermal Striping Phenomena in T-Junction Piping System Using Large Eddy Simulation

2008 ◽  
Author(s):  
Masa-Aki Tanaka ◽  
Hiroyuki Ohshima ◽  
Hideaki Monji
Keyword(s):  
Numerical Simulation ◽  
Heat Conduction ◽  
Three Dimensional ◽  
Piping System ◽  
Fluid Temperature ◽  
Numerical Schemes ◽  
Simulation Code ◽  
Simple Method ◽  
Thermal Striping ◽  
Les Model

In Japan Atomic Energy Agency (JAEA), simulation code “MUGTHES (MUlti Geometry simulation code for THErmal-hydraulic and Structure heat conduction analysis in boundary fitted coordinate)” has been developed to evaluate thermal striping phenomena that are caused by turbulence mixing of fluids in different temperature. MUGTHES employs Boundary Fitted Coordinate (BFC) system to treat complex geometries in power plants. And MUGTHES can deal with three-dimensional transient thermal-hydraulic problem coupled with three-dimensional transient heat conduction in the surrounding structure in consideration of conjugated heat transfer. In this paper, numerical schemes for thermal-hydraulic simulation employed in MUGTHES are described including LES model. A simple method to limit numerical oscillation is adopted in energy equation solving process. A new iterative method to solve Poisson equation in BFC system is developed for effective transient calculations. This method is based on BiCGSTAB method and SOR technique. As the code validation of MUGTHES, a numerical simulation in a T-junction piping system with LES approach was conducted. Numerical results related to velocity and fluid temperature distributions were compared with an existing water experimental data and the applicability of numerical schemes with LES model in MUGTHES to the thermal striping phenomenon was confirmed.

scholarly journals Direct Numerical Simulation of Flow around a Circular Cylinder Controlled Using Plasma Actuators

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Taichi Igarashi ◽  
Hiroshi Naito ◽  
Koji Fukagata
Keyword(s):  
Numerical Simulation ◽  
Circular Cylinder ◽  
Direct Numerical Simulation ◽  
Drag Reduction ◽  
Three Dimensional ◽  
Reduction Rate ◽  
Plasma Actuators ◽  
Two Dimensional ◽  
Freestream Velocity ◽  
The Mean

Flow around a circular cylinder controlled using plasma actuators is investigated by means of direct numerical simulation (DNS). The Reynolds number based on the freestream velocity and the cylinder diameter is set atReD=1000. The plasma actuators are placed at±90° from the front stagnation point. Two types of forcing, that is, two-dimensional forcing and three-dimensional forcing, are examined and the effects of the forcing amplitude and the arrangement of plasma actuators are studied. The simulation results suggest that the two-dimensional forcing is primarily effective in drag reduction. When the forcing amplitude is higher, the mean drag and the lift fluctuations are suppressed more significantly. In contrast, the three-dimensional forcing is found to be quite effective in reduction of the lift fluctuations too. This is mainly due to a desynchronization of vortex shedding. Although the drag reduction rate of the three-dimensional forcing is slightly lower than that of the two-dimensional forcing, considering the power required for the forcing, the three-dimensional forcing is about twice more efficient.

Modeling of low-cement extruded curb of concrete-faced rockfill dam

2011 ◽  
Vol 48 (1) ◽  
pp. 89-97 ◽  
Author(s):  
Ga Zhang ◽  
Jian-Min Zhang
Keyword(s):  
Numerical Simulation ◽  
Damage Model ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Direct Simulation ◽  
Construction Technique ◽  
Displacement Analysis ◽  
Rockfill Dam ◽  
The Face ◽  
Cushion Layer

As the key structure of a practical construction technique, the low-cement extruded curb has been widely used in recent concrete-faced rockfill dams (CFRDs). The extruded curb exhibits significant interactions with the neighboring gravels and with the face slab. These interactions were investigated using element tests, and a new model was proposed. This model is composed of three parts: (i) the equivalent slab that is described using an ideal elastoplasticity model, (ii) the equivalent interface between the curb and the gravel cushion layer that is described using an elastoplasticity damage model, and (iii) the interface between the curb and the face slab that is described using a modified ideal elastoplasticity model. This model was verified via a two-dimensional numerical simulation of an ideal CFRD to capture the main behavior of the extruded curb with interactions between the extruded curb and the neighboring soil – face slab, employing a significantly smaller number of elements and a shorter calculation than direct simulation. The model was used to perform a three-dimensional stress–displacement analysis of the Bakun CFRD (205 m in height), and the results showed that the extruded curb causes a change in the stress of the face slab.

scholarly journals Numerical simulation of mixing by Rayleigh–Taylor and Richtmyer–Meshkov instabilities

1994 ◽  
Vol 12 (4) ◽  
pp. 725-750 ◽  
Author(s):  
D.L. Youngs
Keyword(s):  
Numerical Simulation ◽  
Turbulence Model ◽  
Turbulent Mixing ◽  
Inertial Confinement Fusion ◽  
Three Dimensional ◽  
Small Scale ◽  
Inertial Confinement ◽  
Two Dimensional ◽  
Confinement Fusion ◽  
Icf Target

Rayleigh-Taylor (RT) and Richtmyer–Meshkov (RM) instabilities at the pusher–fuel interface in inertial confinement fusion (ICF) targets may significantly degrade thermonuclear burn. Present-day supercomputers may be used to understand the fundamental instability mechanisms and to model the effect of the ensuing mixing on the performance of the ICF target. Direct three-dimensional numerical simulation is used to investigate turbulent mixing due to RT and RM instability in simple situations. A two-dimensional turbulence model is used to assess the effect of small-scale turbulent mixing in the axisymmetric implosion of an idealized ICF target.

Small-scale structure of two-dimensional magnetohydrodynamic turbulence

1979 ◽  
Vol 90 (1) ◽  
pp. 129-143 ◽  
Author(s):  
Steven A. Orszag ◽  
Cha-Mei Tang
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Three Dimensional ◽  
Scale Structure ◽  
Magnetohydrodynamic Flow ◽  
Small Scale ◽  
Two Dimensional ◽  
Magnetohydrodynamic Turbulence ◽  
Hydrodynamic Turbulence ◽  
Small Scale Structure

The formation of singularities in two-dimensional magnetohydrodynamic flow is investigated by direct numerical simulation. It is shown that two-dimensional magnetohydrodynamic turbulence is not as singular as three-dimensional hydrodynamic turbulence (in the sense that it has a less highly excited small-scale structure) but that it is more singular than two-dimensional hydrodynamic turbulence.

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