scholarly journals An Experiment-Based Simplified Method for the Model of Building Groups in CFD Simulation

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Hongling Guo ◽  
Ying Zhou ◽  
Yingxin Li ◽  
Zhihui Zhang ◽  
Heng Li
Keyword(s):  
Large Scale ◽  
Cfd Simulation ◽  
Orthogonal Experiment ◽  
Simulation Method ◽  
Edge Length ◽  
Basic Unit ◽  
Simplified Method ◽  
Value Range ◽  
Interval Distance ◽  
Wind Simulation

Computational Fluid Dynamics (CFD) has been widely used in the simulation and analysis of community or urban wind environments. However, the CFD-based wind simulation of large-scale building groups usually consumes a lot of computing resources with high computing costs. To improve the efficiency of CFD-based wind simulation, this paper presents an experiment-based simplified method for the model of building groups. Two rectangular buildings are adopted as the basic unit and four control parameters (B/L, W/L, H/L, and D/L) are selected as the experiment factors to analyze the geometrical relationship of the two buildings. Note that L, W, and H, respectively, represent the windward edge length, width, and height of a building, B is building interval distance, and D is the distance between two building center axes. Then, a single factor experiment and an orthogonal experiment are designed and performed to determine the reasonable value range of each factor. Based on the experiment results and actual situation, the value ranges of four factors for the simplification of building group models are determined as follows: B/L∈{0, 1.5}, W/L∈{0, 2}, D/L∈{0, 0.25}, and H/L∈{0, 1}. Furthermore, a real case is presented to evaluate the performance of the proposed simplified method. The results indicate that the simplified method is able to improve the efficiency of CFD-based wind simulation of building groups, with the number of buildings decreasing from 620 to 395 (by 36.3%), and the number of tetrahedral grids decreasing from 8,832,199 to 7,766,778 (by 12.1%). Thus, this research contributes to the CFD-based wind simulation method of large-scale building groups and the analysis of the urban wind environment.

Optimze the Structure of Impeller for Stirred Bioreactor

2013 ◽  
Vol 694-697 ◽  
pp. 148-153 ◽  
Author(s):  
Li Kuan Zhu ◽  
Bo Yan Song ◽  
Zhen Long Wang ◽  
Yu Kui Wang
Keyword(s):  
Fluid Dynamics ◽  
Flow Field ◽  
Shear Force ◽  
Large Scale ◽  
Cfd Simulation ◽  
Simulation Method ◽  
Stirred Bioreactor ◽  
Anticlockwise Rotation ◽  
Computational Fluid Dynamics Cfd ◽  
Large Scale Culture

This paper mainly makes comparative analysis on four main types of blade in stirred bioreactor by Computational Fluid Dynamics(CFD) simulation. Firstly we establish simulation method suited for stirred bioreactor, then simulate the velocity and shear force of flow field in the bioreactor. No matter from flow field mixing or shear force aspect, Elephant Ear blades is the most suitable for cell large scale culture. At last, it optimizes the installation method and angle of Elephant Ear blades. It concludes that anticlockwise rotation and 45°installation angle is the optimum.

A real-time control method-based simulation for high-speed trains on large-scale rail network

2017 ◽  
Vol 28 (10) ◽  
pp. 1750126 ◽  
Author(s):  
Yutong Liu ◽  
Chengxuan Cao ◽  
Yaling Zhou ◽  
Ziyan Feng
Keyword(s):  
Real Time ◽  
Traffic Flow ◽  
High Speed ◽  
Large Scale ◽  
Simulation Method ◽  
Real Time Control ◽  
Rail Network ◽  
Time Control ◽  
High Speed Trains ◽  
Rail Traffic

In this paper, an improved real-time control model based on the discrete-time method is constructed to control and simulate the movement of high-speed trains on large-scale rail network. The constraints of acceleration and deceleration are introduced in this model, and a more reasonable definition of the minimal headway is also presented. Considering the complicated rail traffic environment in practice, we propose a set of sound operational strategies to excellently control traffic flow on rail network under various conditions. Several simulation experiments with different parameter combinations are conducted to verify the effectiveness of the control simulation method. The experimental results are similar to realistic environment and some characteristics of rail traffic flow are also investigated, especially the impact of stochastic disturbances and the minimal headway on the rail traffic flow on large-scale rail network, which can better assist dispatchers in analysis and decision-making. Meanwhile, experimental results also demonstrate that the proposed control simulation method can be in real-time control of traffic flow for high-speed trains not only on the simple rail line, but also on the complicated large-scale network such as China’s high-speed rail network and serve as a tool of simulating the traffic flow on large-scale rail network to study the characteristics of rail traffic flow.

Thermo-mechanical coupling particle simulation of three-dimensional large-scale non-isothermal problems

2017 ◽  
Vol 34 (5) ◽  
pp. 1551-1571 ◽  
Author(s):  
Ming Xia
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Simulation Method ◽  
Particle Simulation ◽  
Similarity Criteria ◽  
Particle Model ◽  
Length Scale ◽  
Content Type ◽  
Mechanical Coupling ◽  
Particle Simulation Method

Purpose The main purpose of this paper is to present a comprehensive upscale theory of the thermo-mechanical coupling particle simulation for three-dimensional (3D) large-scale non-isothermal problems, so that a small 3D length-scale particle model can exactly reproduce the same mechanical and thermal results with that of a large 3D length-scale one. Design/methodology/approach The objective is achieved by following the scaling methodology proposed by Feng and Owen (2014). Findings After four basic physical quantities and their similarity-ratios are chosen, the derived quantities and its similarity-ratios can be derived from its dimensions. As the proposed comprehensive 3D upscale theory contains five similarity criteria, it reveals the intrinsic relationship between the particle-simulation solution obtained from a small 3D length-scale (e.g. a laboratory length-scale) model and that obtained from a large 3D length-scale (e.g. a geological length-scale) one. The scale invariance of the 3D interaction law in the thermo-mechanical coupled particle model is examined. The proposed 3D upscale theory is tested through two typical examples. Finally, a practical application example of 3D transient heat flow in a solid with constant heat flux is given to illustrate the performance of the proposed 3D upscale theory in the thermo-mechanical coupling particle simulation of 3D large-scale non-isothermal problems. Both the benchmark tests and application example are provided to demonstrate the correctness and usefulness of the proposed 3D upscale theory for simulating 3D non-isothermal problems using the particle simulation method. Originality/value The paper provides some important theoretical guidance to modeling 3D large-scale non-isothermal problems at both the engineering length-scale (i.e. the meter-scale) and the geological length-scale (i.e. the kilometer-scale) using the particle simulation method directly.

Research on CFD Simulation of the Cement Slurry Mixer

2012 ◽  
Vol 621 ◽  
pp. 196-199
Author(s):  
Shui Ping LI ◽  
Ya Li Yuan ◽  
Lu Gang Shi
Keyword(s):  
Flow Field ◽  
High Performance ◽  
Cfd Simulation ◽  
Structural Parameters ◽  
Internal Flow ◽  
Simulation Method ◽  
Cement Slurry ◽  
Fluid Machinery ◽  
Computational Fluid Dynamics Cfd ◽  
Machinery Design

Numerical simulation method of the internal flow field of fluid machinery has become an important technology in the study of fluid machinery design. In order to obtain a high-performance cement slurry mixer, computational fluid dynamics (CFD) techniques are used to simulate the flow field in the mixer, and the simulation results are studied. According to the analysis results, the structural parameters of the mixer are modified. The results show the mixer under the revised parameters meet the design requirements well. So CFD analysis method can shorten design period and provide valuable theoretical guidance for the design of fluid machinery.

Numerical Simulation Study on Thermal-Hydraulic Performances of Vehicular Radiator Heat Transfer Units

2012 ◽  
Vol 538-541 ◽  
pp. 2061-2066
Author(s):  
Yang Zheng ◽  
Bao Lan Xiao ◽  
Wei Ming Wu ◽  
Xiao Li Yu ◽  
Guo Dong Lu
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Cooling System ◽  
Experimental Testing ◽  
Orthogonal Experiment ◽  
Simulation Method ◽  
Manufacturing Cost ◽  
Performance Simulation ◽  
Factor Study ◽  
Testing Cost

A radiator is one of the most important components in vehicular cooling system whose excellent fluid flow and heat transfer characteristics guarantees the engine operations. The calculation workload for performance simulation of a whole radiator is too huge due to its size. Experimental study is the conventional method to study radiator performance. This paper put forward a numerical simulation method and radiator heat transfer units were taken as study objects. Orthogonal experiment method was adopted to arrange multi-factor and multi-level calculation schemes. 23 samples with different fin parameters were simulated to investigate their thermal-hydraulic performances. Compared with experimental testing, this method greatly reduced sample manufacturing cost and testing cost, and offered data support for the effect factor study of radiator heat transfer units.

scholarly journals Parallel Motion Simulation of Large-Scale Real-Time Crowd in a Hierarchical Environmental Model

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Xin Wang ◽  
Jianhua Zhang ◽  
Massimo Scalia
Keyword(s):  
Real Time ◽  
Large Scale ◽  
Simulation Method ◽  
Crowd Simulation ◽  
Motion Path ◽  
Motion Simulation ◽  
Environmental Model ◽  
Parallel Methods ◽  
Parallel Motion ◽  
Methods Numerical

This paper presents a parallel real-time crowd simulation method based on a hierarchical environmental model. A dynamical model of the complex environment should be constructed to simulate the state transition and propagation of individual motions. By modeling of a virtual environment where virtual crowds reside, we employ different parallel methods on a topological layer, a path layer and a perceptual layer. We propose a parallel motion path matching method based on the path layer and a parallel crowd simulation method based on the perceptual layer. The large-scale real-time crowd simulation becomes possible with these methods. Numerical experiments are carried out to demonstrate the methods and results.

scholarly journals CFD Simulation and Experimental Study on Coupled Motion Response of Ship with Tank in Beam Waves

2022 ◽  
Vol 10 (1) ◽  
pp. 113
Author(s):  
Tao He ◽  
Dakui Feng ◽  
Liwei Liu ◽  
Xianzhou Wang ◽  
Hua Jiang
Keyword(s):  
Working Conditions ◽  
Large Scale ◽  
Cfd Simulation ◽  
Stokes Equations ◽  
Body Motion ◽  
Time Step ◽  
Coupled Motion ◽  
Motion Response ◽  
Time Step Size ◽  
Tank Sloshing

Tank sloshing is widely present in many engineering fields, especially in the field of marine. Due to the trend of large-scale liquid cargo ships, it is of great significance to study the coupled motion response of ships with tanks in beam waves. In this study, the CFD (Computational Fluid Dynamics) method and experiments are used to study the response of a ship with/without a tank in beam waves. All the computations are performed by an in-house CFD solver, which is used to solve RANS (Reynold Average Navier-Stokes) equations coupled with six degrees-of-freedom solid-body motion equations. The Level Set Method is used to solve the free surface. Verification work on the grid number and time step size has been conducted. The simulation results agree with the experimental results well, which shows that the numerical method is accurate enough. In this paper, several different working conditions are set up, and the effects of the liquid height in the tank, the size of the tank and the wavelength ratio of the incident wave on the ship’s motion are studied. The results show the effect of tank sloshing on the ship’s motion in different working conditions.

Effects of Wet Activation Process Parameters on Surface Hydrophilicity in Silicon Direct Wafer Bonding

2012 ◽  
Vol 235 ◽  
pp. 250-253
Author(s):  
Lei Nie ◽  
Jun Xing Yu ◽  
Kun Zhang
Keyword(s):  
Wafer Bonding ◽  
Orthogonal Experiment ◽  
Volume Ratio ◽  
Holding Time ◽  
Activation Process ◽  
Analysis Method ◽  
Range Analysis ◽  
Surface Hydrophilicity ◽  
Direct Wafer Bonding ◽  
Value Range

Wet activation is a very important step in silicon direct wafer bonding process and a optimized activation process is desirable to improve the surface hydrophilicity. Therefore the pivotal parameters of activation process were investigated which were volume ratio, holding time and treat temperature. A orthogonal experiment array was designed to reveal the effects of these parameters and the experiment results were analyzed by range analysis method. The analysis results indicted among those three parameters, everyone had intimidate relationship with surface hydrophilicity, which was indexed by contact angle. And higher concentration, longer holding time and higher treating temperature in possible value range were more desirable. Based on these conclusions, optimized activation process was desigened using which void-free bonding was realized.

An Extensive Logic Simulation Method of Very Large Scale Computer Design

1986 ◽  
Author(s):  
M. Miyoshi ◽  
Y. Ooshima ◽  
A. Sugiyama ◽  
N. Onizuka ◽  
N. Amano
Keyword(s):  
Large Scale ◽  
Simulation Method ◽  
Computer Design ◽  
Logic Simulation
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