scholarly journals A Generalized Reduced Fluid Dynamic Model for Flow Fields and Electrodes in Redox Flow Batteries

2021 ◽  
Author(s):  
Ziqiang Cheng ◽  
Kevin Tenny ◽  
Alberto Pizzolato ◽  
Antoni Forner-Cuenca ◽  
Vittorio Verda ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Fluid Dynamic ◽  
Fluid Motion ◽  
Maximum Velocity ◽  
Flow Fields ◽  
Three Dimensions ◽  
Modeling Framework ◽  
Plane Flow ◽  
Computational Overhead ◽  
2D Model

High dimensional models typically require a large computational overhead for multiphysics applications, which hamper their use for broad-sweeping domain interrogation. Herein, we develop a modeling framework to capture the through-plane fluid dynamic response of electrodes and flow fields in a redox flow cell, generating a computationally inexpensive two-dimensional (2D) model. We leverage a depth averaging approach that also accounts for variations in out-of-plane fluid motion and departures from Darcy’s law that arise from averaging across three-dimensions (3D). Our Resulting depth-averaged 2D model successfully predict the fluid dynamic response of arbitrary in-plane flow field geometries, with discrepancies of < 5% for both maximum velocity and pressure drop. This corresponds to reduced computational expense, as compared to 3D representations (< 1% of duration and 10% of RAM usage), providing a platform to screen and optimize a diverse set of cell geometries.

Nonlinear behavior of Helmholtz resonator with a compliant wall for low frequency, broadband noise control

2021 ◽  
pp. 1-29
Author(s):  
Maya Pishvar ◽  
Ryan L Harne
Keyword(s):  
Dynamic Response ◽  
Low Frequency ◽  
Nonlinear Behavior ◽  
Helmholtz Resonator ◽  
Broadband Noise ◽  
Sound Attenuation ◽  
Wall Material ◽  
Modeling Framework ◽  
Compliant Wall ◽  
Broadband Sound

Abstract Low frequency sound attenuation is often pursued using Helmholtz resonators (HRs). The introduction of a compliant wall around the acoustic cavity results in a two-degree-of-freedom (2DOF) system capable of more broadband sound absorption. In this study, we report the amplitude-dependent dynamic response of a compliant walled HR and investigate the effectiveness of wall compliance to improve the absorption of sound in linear and nonlinear regimes. The acoustic-structure interactions between the conventional Helmholtz resonator and the compliant wall result in non-intuitive responses when acted on by nonlinear amplitudes of excitation pressure. This paper formulates and studies a reduced order model to characterize the nonlinear dynamic response of the 2DOF HR with a compliant wall compared to that of a conventional rigid HR. Validated by experimental evidence, the modeling framework facilitates an investigation of strategies to achieve broadband sound attenuation, including by selection of wall material, wall thickness, geometry of the HR, and other parameters readily tuned by system design. The results open up new avenues for the development of efficient acoustic resonators exploiting the deflection of a compliant wall for suppression of extreme noise amplitudes.

scholarly journals Fluid Dynamic Response of the Russia Seismically Differing Regions to the Global Geodynamics Processes

2012 ◽  
Vol 03 (04) ◽  
pp. 767-771 ◽  
Author(s):  
Valera P. Rudakov ◽  
Pavel P. Firstov ◽  
Vladislav V. Tsyplakov
Keyword(s):  
Dynamic Response ◽  
Fluid Dynamic ◽  
Global Geodynamics

Analysis of Dynamic Response for Piezoelectric Vibration Converter by Finite Element Simulation

2007 ◽  
Vol 336-338 ◽  
pp. 335-337
Author(s):  
Xiang Cheng Chu ◽  
Ren Bo Yan ◽  
Wen Gong ◽  
Long Tu Li
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Finite Elements ◽  
Dynamic Response ◽  
Finite Element Modeling ◽  
Three Dimensions ◽  
Dynamic Motion ◽  
Element Simulation ◽  
Piezoelectric Coupling ◽  
Piezoelectric Vibration

The dynamic behavior of a vibration converter of an ultrasonic motor is described using finite element method. Tetrahedral finite elements with three dimensions are formulated with the effects of piezoelectric coupling. And the solution of the coupled electroelastic equations of dynamic motion is presented. The simulated response of the vibration converter is calculated, and shows excellent consistency with experimental results, which proved that finite element modeling is a good approach to optimize piezoelectric apparatus design. A gradual optimized method is employed to ascertain the most compatible structure.

The Role of Simulation in the Development of a Fast-Actuation Solenoid C.R. Injection System

2004 ◽  
Author(s):  
Gian Marco Bianchi ◽  
Piero Pelloni ◽  
Giovanni Osbat ◽  
Marco Parotto ◽  
Rita Di Gioia ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Control Strategies ◽  
Fluid Dynamic ◽  
Numerical Approach ◽  
Linear Analysis ◽  
Operating Conditions ◽  
System Model ◽  
Injection System ◽  
Multiple Injection ◽  
Pressure Regulator

Upcoming Euro 4 and Euro 5 emission standards are increasing efforts on injection system developments in order to improve mixture quality and combustion efficiency. The target features of advanced injection system are related to their capability of operating multiple injection with a precise control of amount of fuel injected, low cycle-by-cycle variability and life drift, within flexible strategies. In order to accomplish this task, performance must be optimised since injection system concept development by acting on. The extensive use of numerical approach has been identified as a necessary integration to experiments in order to put on the market high quality injection system accomplishing strict engine control strategies. The modelling approach allows focusing the experimental campaign only on critical issues saving time and costs, furthermore it is possible to deeply understand inner phenomena that cannot be measured. The lump/ID model of the whole system built into the AMESim® code was presented in previous works: particular attention was devoted in the simulation of the electromagnetic circuits, actual fluid-dynamic forces acting on needle surfaces and discharge coefficients, evaluated by means 3D-CFD simulations. In order to assess new injection system dynamic response under multiple injection strategies reproducing actual engine operating conditions it is necessary to find to proper model settings. In this work the integration between the injector and the system model, which comprehends the pump, the pressure regulator, the rail and the connecting-pipes, will be presented. For reproducing the dynamic response of he whole system will be followed a step-by-step approach in order to prevent modelling inaccuracies. Firstly will be presented the linear analysis results performed in order to find injection system own natural frequencies. Secondly based on linear analysis results will be found proper injection system model settings for predicting dynamic response to external excitations, such as pump perturbations, pressure regulator dynamics and injection pulses. Thirdly experimental results in terms of instantaneous flow rate and integrated injected volume for different operating conditions will be presented in order to highlight the capability of the modelling methodology in addressing the new injection system design.

Experimental heat transfer characteristics of a liquid in Couette motion and with Taylor vortices

1961 ◽  
Vol 261 (1305) ◽  
pp. 215-226 ◽  
Keyword(s):  
Heat Transfer ◽  
Reverse Flow ◽  
Fluid Dynamic ◽  
Fluid Motion ◽  
Heat Transfer Characteristics ◽  
Radial Temperature ◽  
Transfer Characteristics ◽  
Experimental Heat ◽  
Concentric Cylinders ◽  
Primary Fluid

The heat transfer characteristics of water in rotational motion between horizontal concentric cylinders has been studied. Primary fluid motion due to rotation of the inner cylinders alone, and due to rotation of inner cylinder with reverse flow caused by a divider, has been considered experimentally for two ratios of annulus width to inner cylinder radius. The results for two geometries and two primary fluid dynamic conditions are correlated by a parameter related to the generalized stability parameter. Radial temperature profiles are given and are shown to be effective in indicating secondary flow patterns.

Shallow-water sloshing in vessels undergoing prescribed rigid-body motion in three dimensions

2011 ◽  
Vol 667 ◽  
pp. 474-519 ◽  
Author(s):  
HAMID ALEMI ARDAKANI ◽  
THOMAS J. BRIDGES
Keyword(s):  
Rigid Body ◽  
Shallow Water ◽  
Fluid Motion ◽  
Rigid Body Motion ◽  
Body Motion ◽  
Three Dimensions ◽  
Alternating Direction Implicit ◽  
Alternating Direction ◽  
Implicit Finite Difference Scheme ◽  
Shallow Water Models

New shallow-water equations (SWEs), for sloshing in three dimensions (two horizontal and one vertical) in a vessel which is undergoing rigid-body motion in 3-space, are derived. The rigid-body motion of the vessel (roll–pitch–yaw and/or surge–sway–heave) is modelled exactly and the only approximations are in the fluid motion. The flow is assumed to be inviscid but vortical, with approximations on the vertical velocity and acceleration at the surface. These equations improve previous shallow-water models. The model also extends to three dimensions the essence of the Penney–Price–Taylor theory for the highest standing wave. The surface SWEs are simulated using a split-step alternating direction implicit finite-difference scheme. Numerical experiments are reported, including comparisons with existing results in the literature, and simulations with vessels undergoing full 3-D rotations.

Numerical study of flow fields in an airway closure model

2011 ◽  
Vol 677 ◽  
pp. 483-502 ◽  
Author(s):  
C.-F. TAI ◽  
S. BIAN ◽  
D. HALPERN ◽  
Y. ZHENG ◽  
M. FILOCHE ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Normal Stress ◽  
Numerical Study ◽  
Stress Gradient ◽  
Fluid Motion ◽  
Flow Fields ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Wall Shear

The liquid lining in small human airways can become unstable and form liquid plugs that close off the airways. Direct numerical simulations are carried out on an airway model to study this airway instability and the flow-induced stresses on the airway walls. The equations governing the fluid motion and the interfacial boundary conditions are solved using the finite-volume method coupled with the sharp interface method for the free surface. The dynamics of the closure process is simulated for a viscous Newtonian film with constant surface tension and a passive core gas phase. In addition, a special case is examined that considers the core dynamics so that comparisons can be made with the experiments of Bian et al. (J. Fluid Mech., vol. 647, 2010, p. 391). The computed flow fields and stress distributions are consistent with the experimental findings. Within the short time span of the closure process, there are large fluctuations in the wall shear stress. Furthermore, dramatic velocity changes in the film during closure indicate a steep normal stress gradient on the airway wall. The computational results show that the wall shear stress, normal stress and their gradients during closure can be high enough to injure airway epithelial cells.

Classification of evidence in decision-analytic models of cost-effectiveness: A content analysis of published reports

2010 ◽  
Vol 26 (4) ◽  
pp. 458-462 ◽  
Author(s):  
Suzy Paisley
Keyword(s):  
Content Analysis ◽  
Cost Effectiveness ◽  
Methodological Approach ◽  
Model Development ◽  
Three Dimensions ◽  
Model Parameters ◽  
Modeling Framework ◽  
Diverse Range ◽  
Analytic Models

Objectives: The aim of this study was to assess systematically the scope of evidence and purposes for which evidence is used in decision-analytic models of cost-effectiveness and to assess the implications for search methods.Methods: A content analysis of published reports of models was undertaken. Details of cited sources were extracted and categorized according to three dimensions; type of information provided by the evidence, type of source from which the evidence was drawn and type of modeling activity supported by the evidence. The analysis was used to generate a classification of evidence. Relationships within and between the categories within the classification were sought and the implications for searching considered.Results: The classification generated fourteen types of information, seven types of sources of evidence and five modeling activities supported by evidence. A broad range of evidence was identified drawn from a diverse range of sources including both research-based and non–research-based sources. The use of evidence was not restricted to the population of model parameters but was used to inform the development of the modeling framework and to justify the analytical and methodological approach.Conclusions: Decision-analytic models use evidence to support all aspects of model development. The classification of evidence defines in depth the role of evidence in modeling. It can be used to inform the systematic identification of evidence.

Effect of Baffle Design Parameters on Fluid Dynamic Response of a Coal Classifier

2014 ◽  
Vol 3 (0) ◽  
pp. 15
Author(s):  
Hamid Khoshdast ◽  
Hami Khoshdast ◽  
Vahideh Shojaei
Keyword(s):  
Dynamic Response ◽  
Fluid Dynamic ◽  
Design Parameters

Design, Simulation and Development of Gold Microneedles Patch

2013 ◽  
Author(s):  
Shahzadi Tayyaba ◽  
Muhammad Waseem Ashraf ◽  
Nitin Afzulpurkar ◽  
Muhammad Khaleeq ur Rahman
Keyword(s):  
Fluid Transport ◽  
Fluid Dynamic ◽  
Human Life ◽  
Maximum Velocity ◽  
Ease Of Use ◽  
Chicken Skin ◽  
Microfluidic Analysis ◽  
Microneedle Patch ◽  
Micro Electromechanical System ◽  
Health Discipline

Technological advancements are essential for all fields of life particularly in health discipline to test and analyze the biological and biomedical samples. Biological micro electromechanical system (Bio-MEMS) based healthcare technologies are handy to make human life comfortable and snug by ease of use, eradicating pain, reducing risk of diseases, improving diagnosis process and treatments techniques. In this study the design, simulation and development of piezoelectricaly actuated microfluidic device (gold needle patch) has been presented. The simulation of skin insertion using gold needle into skin to study the effects of skin piercing and optimize the design of needle has been conducted in ansys autodyne by making 3D model with applied force 0.4 to 0.9 N at the tip area of needle. The microfluidic analysis of 3×3 microneedle patch has been carry out in ansys workbench using computational fluid dynamic (CFX) environment. The maximum velocity 2.015 e4 m/Sec has been achieved. After the successful development of gold needles patch, the fluid transport and insertion test of piezoelectricaly actuated patch also has been conducted using chicken skin.

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