A Numerical Scheme for Investigating the Influence of the Three Dimensional Geometrical Features of Porous Polymeric Foam on Its Sound Absorbing Behavior

2010 ◽  
Vol 96 (2) ◽  
pp. 239-246 ◽  
Author(s):  
L. Boeckx ◽  
M. Brennan ◽  
K. Verniers ◽  
J. Vandenbroeck
Keyword(s):  
Numerical Scheme ◽  
Three Dimensional ◽  
Polymeric Foam ◽  
Geometrical Features

scholarly journals FAÇADE DESIGN EFFECT ON CROSS-VENTILATION IN TAIWANESE SCHOOL BUILDINGS

2013 ◽  
Vol 8 (2) ◽  
pp. 90-111 ◽  
Author(s):  
W.H. Chiang ◽  
H.H. Hsu ◽  
J.S. Huang
Keyword(s):  
Numerical Scheme ◽  
Wind Profile ◽  
Incident Angle ◽  
Three Dimensional ◽  
Windward Side ◽  
School Buildings ◽  
Breathing Zone ◽  
Air Exchange Rate ◽  
Computational Fluid Dynamics Cfd ◽  
Shading Devices

This study performed a three-dimensional numerical prediction for the induced airflow patterns and mean age of air (MAGE) around and inside a naturally ventilated school building, while accounting for the wind profile effect. Various fenestrations, hallways, and shading devices on the windward side of building were analyzed to determine how they affected wind velocity, the incident angle of airflow, and MAGE distribution inside classrooms. The numerical scheme is based on a commercial computational fluid dynamics (CFD) code, PHOENICS. The incline of incoming wind was observed on higher floors that decreased the air exchange rate in the simulated room. The inclined airflow could be effectively deflected downward through the breathing zone by hallways, 1.2-m shades as overhangs, and 0.6-m louvers. Based on this research, an appropriate combination of external attachments on the windward side of building façade can be utilized to enhance ventilation in school buildings. (See Appendix 1 for nomenclature.)

scholarly journals Modeling of the Mechanical Behavior of 3D Bioplotted Scaffolds Considering the Penetration in Interlocked Strands

2018 ◽  
Vol 8 (9) ◽  
pp. 1422 ◽  
Author(s):  
Saman Naghieh ◽  
M. Sarker ◽  
Mohammad Karamooz-Ravari ◽  
Adam McInnes ◽  
Xiongbiao Chen
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Mechanical Behavior ◽  
Model Development ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Hydrogel Scaffolds ◽  
Important Index ◽  
Geometrical Features ◽  
Scaffold Structure

Three-dimensional (3D) bioplotting has been widely used to print hydrogel scaffolds for tissue engineering applications. One issue involved in 3D bioplotting is to achieve the scaffold structure with the desired mechanical properties. To overcome this issue, various numerical methods have been developed to predict the mechanical properties of scaffolds, but limited by the imperfect representation of one key feature of scaffolds fabricated by 3D bioplotting, i.e., the penetration or fusion of strands in one layer into the previous layer. This paper presents our study on the development of a novel numerical model to predict the elastic modulus (one important index of mechanical properties) of 3D bioplotted scaffolds considering the aforementioned strand penetration. For this, the finite element method was used for the model development, while medium-viscosity alginate was selected for scaffold fabrication by the 3D bioplotting technique. The elastic modulus of the bioplotted scaffolds was characterized using mechanical testing and results were compared with those predicted from the developed model, demonstrating a strong congruity between them. Once validated, the developed model was also used to investigate the effect of other geometrical features on the mechanical behavior of bioplotted scaffolds. Our results show that the penetration, pore size, and number of printed layers have significant effects on the elastic modulus of bioplotted scaffolds; and also suggest that the developed model can be used as a powerful tool to modulate the mechanical behavior of bioplotted scaffolds.

An Investigation Into Nonlinear Growth Rate of Two-Dimensional and Three-Dimensional Single-Mode Richtmyer–Meshkov Instability Using an Arbitrary-Lagrangian–Eulerian Algorithm

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Mike Probyn ◽  
Ben Thornber ◽  
Dimitris Drikakis ◽  
David Youngs ◽  
Robin Williams
Keyword(s):  
Growth Rate ◽  
Numerical Scheme ◽  
Initial Conditions ◽  
Numerical Study ◽  
Three Dimensional ◽  
Single Mode ◽  
Computational Time ◽  
Initial Growth ◽  
Arbitrary Lagrangian Eulerian ◽  
Layer Width

This paper presents an investigation into the use of a moving mesh algorithm for solving unsteady turbulent mixing problems. The growth of a shock induced mixing zone following reshock, using an initial setup comparable to that of existing experimental work, is used to evaluate the behavior of the numerical scheme for single-mode Richtmyer–Meshkov instability (SM-RMI). Subsequently the code is used to evaluate the growth rate for a range of different initial conditions. The initial growth rate for three-dimensional (3D) SM Richtmyer–Meshkov is also presented for a number of different initial conditions. This numerical study details the development of the mixing layer width both prior to and after reshock. The numerical scheme used includes an arbitrary Lagrangian–Eulerian grid motion which is successfully used to reduce the mesh size and computational time while retaining the accuracy of the simulation results. Varying initial conditions shows that the growth rate after reshock is independent of the initial conditions for a SM provided that the initial growth remains in the linear regime.

INFLOW/OUTFLOW CONDITIONS FOR TIME-HARMONIC INTERNAL FLOWS

2002 ◽  
Vol 10 (02) ◽  
pp. 155-182 ◽  
Author(s):  
OLIVER V. ATASSI ◽  
AMR A. ALI
Keyword(s):  
Acoustic Waves ◽  
Numerical Scheme ◽  
Truncation Error ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Internal Flows ◽  
Vortex Sheets ◽  
Dimensional Interaction ◽  
Time Harmonic ◽  
Annular Cascade

Inflow/Outflow conditions are formulated for time-harmonic waves in a duct governed by the Euler equations. These conditions are used to compute the propagation of acoustic and vortical disturbances and the scattering of vortical waves into acoustic waves by an annular cascade. The outflow condition is expressed in terms of the pressure, thus avoiding the velocity discontinuity across any vortex sheets. The numerical solutions are compared with the analytical solutions for acoustic and vortical wave propagation with and without the presence of vortex sheets. Grid resolution studies are also carried out to discern the truncation error of the numerical scheme from the error associated with numerical reflections at the boundary. It is observed that even with the use of exponentially accurate boundary conditions, the dispersive characteristics of the numerical scheme may result in small reflections from the boundary that slow convergence. Finally, the three-dimensional interaction of a wake with a flat plate cascade is computed and the aerodynamic and aeroacoustic results are compared with those of lifting surface methods.

An Accurate and Efficient Euler Solver for Three-Dimensional Turbomachinery Flows

1986 ◽  
Author(s):  
C. F. Shieh ◽  
R. A. Delaney
Keyword(s):  
Numerical Solution ◽  
Euler Equations ◽  
Numerical Scheme ◽  
Three Dimensional ◽  
Curvilinear Coordinates ◽  
Analysis Method ◽  
Surfaces Of Revolution ◽  
Conservative Form ◽  
Turbine Cascades ◽  
Euler Solver

Accurate and efficient Euler equation numerical solution techniques are presented for analysis of three-dimensional turbomachinery flows. These techniques include an efficient explicit hopscotch numerical scheme for solution of the 3-D time-dependent Euler equations and an O-type body-conforming grid system. The hopscotch scheme is applied to the conservative form of the Euler equations written in general curvilinear coordinates. The grid is constructed by stacking from hub to shroud 2-D O-type grids on equally spaced surfaces of revolution. Numerical solution results for two turbine cascades are presented and compared with experimental data to demonstrate the accuracy of the analysis method.

Three Dimensional Fully Localized Waves on Ice-Covered Ocean

2013 ◽  
Author(s):  
Yong Liang ◽  
M.-Reza Alam
Keyword(s):  
Numerical Scheme ◽  
Perturbation Technique ◽  
Three Dimensional ◽  
Multiple Scale ◽  
Governing Equations ◽  
Weakly Nonlinear ◽  
Scale Perturbation ◽  
Speed Of Propagation ◽  
Localized Waves ◽  
Mean Current

We have recently shown [1] that fully-localized three-dimensional wave envelopes (so-called dromions) can exist and propagate on the surface of ice-covered waters. Here we show that the inertia of the ice can play an important role in the size, direction and speed of propagation of these structures. We use multiple-scale perturbation technique to derive governing equations for the weakly nonlinear envelope of monochromatic waves propagating over the ice-covered seas. We show that the governing equations simplify to a coupled set of one equation for the envelope amplitude and one equation for the underlying mean current. This set of nonlinear equations can be further simplified to fall in the category of Davey-Stewartson equations [2]. We then use a numerical scheme initialized with the analytical dromion solution of DSI (i.e. shallow-water and surface-tension dominated regimes of Davey-Stewartson equation) to look for dromion solution of our equations. Dromions can travel over long distances and can transport mass, momentum and energy from the ice-edge deep into the solid ice-cover that can result in the ice cracking/breaking and also in posing dangers to icebreaker ships.

A Pseudo-Spectral Numerical Scheme for the Simulation of Convective Flows

2002 ◽  
Author(s):  
Laila Guessous ◽  
Yuehong Zheng
Keyword(s):  
Variational Formulation ◽  
Numerical Scheme ◽  
Mass Matrix ◽  
Three Dimensional ◽  
Vertical Direction ◽  
The Novel ◽  
Convective Flows ◽  
Development And Validation ◽  
Pseudo Spectral ◽  
Unsteady Channel Flow

This paper focuses on the development and validation of a pseudo-spectral numerical scheme, based on a variational formulation, for the solution of the three-dimensional, time-dependent governing equations in wall bounded forced and natural convective flows. One of the novel aspects of this numerical scheme is the use of rescaled Legendre-Lagrangian interpolants to represent the velocity and temperature in the vertical direction. These interpolants were obtained by dividing the Legendre Lagrangian interpolants of same order by the square root of the corresponding weight used for Gauss-Lobatto quadrature. By rescaling the interpolants in such a manner, the mass matrix resulting from the variational formulation becomes the identity matrix, thus simplifying the numerical algorithm. Two specific problems have been investigated as part of the validation process: Steady and unsteady channel flow driven by an external streamwise oscillating pressure gradient and Rayleigh Be´nard convection. In all cases, comparison with exact solutions and published results yield excellent agreement.

Simulation of Geometry and Heat Transfer in a Thin Wall Produced by Direct Laser Powder Deposition

2011 ◽  
Vol 227 ◽  
pp. 134-137
Author(s):  
Karim Kheloufi ◽  
El Hachemi Amara
Keyword(s):  
Three Dimensional ◽  
Deposition Process ◽  
Thin Wall ◽  
Three Dimensional Model ◽  
Laser Powder Deposition ◽  
Commercial Code ◽  
Geometrical Features ◽  
Direct Laser ◽  
Powder Deposition ◽  
Single Bead

A three dimensional model for direct laser powder deposition process is developed to simulate the geometry and the thermal field in building a single-bead wall (thin-wall). This model was employed using the Fluent commercial code to which several modules were appended (User Defined Functions UDF). The temperature distribution, the geometrical features of the generated structure, and thermal cycles have been carried out. We show that the results analysis can provide guidance for the process parameter selection in LPD. , and develop a base for further residual stress analysis.

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