scholarly journals Study on Bubble Cavitation in Liquids for Bubbles Arranged in a Columnar Bubble Group

2019 ◽  
Vol 9 (24) ◽  
pp. 5292
Author(s):  
Peng-li Zhang ◽  
Shu-yu Lin
Keyword(s):  
Resonance Frequency ◽  
Bubble Growth ◽  
Coupling Effect ◽  
Ultrasonic Field ◽  
Correction Coefficient ◽  
Initial Radius ◽  
Bubble Cavitation ◽  
Fluent Software ◽  
Simulation Results ◽  
Two Bubbles

In liquids, bubbles usually exist in the form of bubble groups. Due to their interaction with other bubbles, the resonance frequency of bubbles decreases. In this paper, the resonance frequency of bubbles in a columnar bubble group is obtained by linear simplification of the bubbles’ dynamic equation. The correction coefficient between the resonance frequency of the bubbles in the columnar bubble group and the Minnaert frequency of a single bubble is given. The results show that the resonance frequency of bubbles in the bubble group is affected by many parameters such as the initial radius of bubbles, the number of bubbles in the bubble group, and the distance between bubbles. The initial radius of the bubbles and the distance between bubbles are found to have more significant influence on the resonance frequency of the bubbles. When the distance between bubbles increases to 20 times the bubbles’ initial radius, the coupling effect between bubbles can be ignored, and after that the bubbles’ resonance frequency in the bubble group tends to the resonance frequency of a single bubble’s resonance frequency. Fluent software is used to simulate the bubble growth, shrinkage, and collapse of five and seven bubbles under an ultrasonic field. The simulation results show that when the bubble breaks, the two bubbles at the outer field first begin to break and form a micro-jet along the axis line of the bubbles. Our methods and conclusions will provide a reference for further simulations and indicate the significance of the prevention or utilization of cavitation.

The Influence of the Convective Terms Discretization Scheme on the Simulation Results of Architectural Numerical Wind Tunnel

2012 ◽  
Vol 204-208 ◽  
pp. 4884-4887
Author(s):  
Jian Feng Wu ◽  
Cai Hua Wang ◽  
Chang Li Song
Keyword(s):  
Numerical Simulation ◽  
Wind Tunnel ◽  
Building Structures ◽  
Discretization Scheme ◽  
Shape Coefficient ◽  
Fluent Software ◽  
Actual Operation ◽  
Simulation Results ◽  
Load Shape ◽  
Numerical Wind Tunnel Method

The numerical simulation of construction is to obtain the desired accuracy. It depends on the theoretical basis of the calculator and selection of the various important factors in the actual operation. For this problem, this paper adopting the current code for the design of building structures as the comparison standard, using the FLUENT software, taking the numerical simulation results of a high building’s wind load shape coefficient of for example, discussing the influence of four kinds of the convective terms discretization scheme, respectively the first-order upwind, the second order upwind , power law and Quadratic upwind interpolation for convective kinematics, on the simulation results of architectural numerical wind tunnel, provides the reference for the rational use of numerical wind tunnel method.

Bow Shock Effect on Particle Transport and Deposition in a Hypersonic Impactor

2003 ◽  
Author(s):  
Omid Abouali ◽  
Goodarz Ahmadi
Keyword(s):  
Computer Simulation ◽  
Flow Field ◽  
Particle Transport ◽  
Operating Conditions ◽  
Bow Shock ◽  
Nano Particles ◽  
Correction Coefficient ◽  
Navier Stokes Equation ◽  
Micro Particles ◽  
Simulation Results

Supersonic/hypersonic impactors are used as a collector and/or size separator of nano- and micro-particles. Thin film and fine line pattern deposition by aerosol jets are other applications of deposition of supersonic/hypersonic impactors. At extremely low backpressures, the exiting flow from a nozzle forms a supersonic free jet. The supersonic jet forms a strong normal shock in the front of the impactor plate. The stagnation pressure, backpressure and distance between the nozzle exit and the impactor plate affect the flow field. Due to the rather complicated flow in the impactor, studies of particle motions in supersonic impactors are rather scarce. In this study the airflow and particle transport and deposition in a supersonic/hypersonic impactor are numerically simulated. The axisymmetric compressible Navier-Stokes equation is solved and the flow properties are evaluated. It is assumed that the particle concentration is dilute, to the extent that the presence of particles does not alter the flow field. Deposition of different size particles under different operating conditions is studied. The importance of drag, lift and Brownian forces on particle motions in supersonic impactors is discussed. Sensitivity of the simulation results to the use of different expressions for the drag force is also examined. A strong bow shock on the flowfield has much effect in drag forces on particles. It is shown that the Stokes-Cunningham drag with variable correction coefficient is most suitable for computer simulation studies of nano-particles in supersonic/hypersonic impactors. The computer simulation results are shown to compare favorably with the experimental data.

Improved Design of Thermal Airflow Process for the Annular Cooler and Fluent Simulation

2010 ◽  
Vol 43 ◽  
pp. 351-356
Author(s):  
Xi Liang Zhang ◽  
Wen Xiang Gao ◽  
Li Qiang Chen ◽  
Jun Xu ◽  
Ai Xin Feng
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Heat Recovery ◽  
Cooling Zone ◽  
Recovery Efficiency ◽  
Gas Emission ◽  
Fluent Simulation ◽  
Fluent Software ◽  
Simulation Results ◽  
Improved Design

Considering the current problems of low temperature of recovered gas, the direct gas emission of the fourth cooling zone in the operation of the annular cooler, thermal airflow process for the annular cooler is improved by analyzing the thermal airflow process and the structure of the annular cooler and using the principle of repeated convective heat transfer. Thus the above-mentioned problem can be solved. Simulation model of its thermal airflow process is established and the simulation results, obtained by using Fluent software, are as follows: the temperature of the gas in the first cooling zone entering the rotary kiln of the improved is about 110°C higher than that of the unimproved, the temperature of the gas in the second cooling zone entering the preheat zone I of the chain grate of the improved is about 150°C higher than that of the unimproved, and the temperature of the gas in the fourth cooling zone entering the downdraft drying zone of the chain grate of the improved is about 50°C higher than that of the unimproved. Pellet heat recovery efficiency is increased significantly.

Research on Tornado Effect of High-Speed Spiral Flow in the Lifting Pipe

2014 ◽  
Vol 955-959 ◽  
pp. 3544-3547
Author(s):  
Jun Tang ◽  
Rui Jie Gao ◽  
Shu Wen Hu
Keyword(s):  
Differential Equation ◽  
High Speed ◽  
Pressure Field ◽  
Tangential Velocity ◽  
Control Element ◽  
Simulation Test ◽  
Spiral Flow ◽  
Fluent Software ◽  
Velocity Equation ◽  
Simulation Results

Through stress analysis of micro control element,pressure differential equation of lifting pipe was deduced,and tornado effect of high-speed spiral flow was discussed. Secondly, fluent software was used, through which the simulation test of lifting pipe was conducted, pressure field and velocity field were got. The results showed that radial velocity equation and tangential velocity equation and axial velocity equation and pressure equation are consistent with the simulation results.

THE EFFECT OF THE GAS INLET ON THE FLUID FIELD DURING FABRICATING HFCVD DIAMOND-COATED CUTTING TOOLS

2014 ◽  
Vol 21 (05) ◽  
pp. 1450068
Author(s):  
BIN SHEN ◽  
SULIN CHEN ◽  
LEI CHENG ◽  
FANGHONG SUN
Keyword(s):  
Initial Velocity ◽  
Coupling Effect ◽  
Cutting Tools ◽  
Chemical Vapor ◽  
Gas Velocity ◽  
Gas Field ◽  
Growth Environment ◽  
Fluid Field ◽  
Flute Surface ◽  
Simulation Results

In the present study, the fluid field in a process of fabricating diamond coated cutting tools using the hot filament chemical vapor deposition (HFCVD) method is investigated using the finite volume method (FVM), in which the effects of the inlet height, gas initial velocity, inlet radius and arrangement are illustrated in terms of the gas velocity magnitude and vector distribution near the filaments and the flute surface of cutting tools. In the simulations, the coupling effect of the temperature and the gas field is also considered by simultaneously calculating the temperature distribution. The simulation results suggest that either shortening the distance between the gas inlet and filaments, or increasing the gas initial velocity is helpful for the reactive gas arriving at filaments surface and being dissociated. Furthermore, increasing the inlet area is able to significantly increase the velocity of gas field around the filaments, as well as produce a much more uniform gas velocity field. Based on this conclusion, two novel multi-inlets setups are proposed to further improve the generated gas field and the simulation results show that the most superior gas field can be achieved with the one including 8 larger central inlets and 24 smaller outskirt inlets. Finally, an actual deposition experiment is carried out and its result indicates that adopting the optimized such inlet arrangement could generate a highly uniform and homogeneous growth environment on whole deposition area.

NEW HIGH INPUT IMPEDANCE VOLTAGE-MODE LOWPASS, BANDPASS AND HIGHPASS FILTER USING CURRENT FEEDBACK AMPLIFIERS

2005 ◽  
Vol 14 (06) ◽  
pp. 1037-1043 ◽  
Author(s):  
NISAR AHMAD SHAH ◽  
MOHD AMIN MALIK
Keyword(s):  
Resonance Frequency ◽  
Input Impedance ◽  
Theoretical Calculations ◽  
High Input ◽  
High Input Impedance ◽  
Current Feedback ◽  
Cascade Connection ◽  
Highpass Filter ◽  
Simulation Results ◽  
Passive Sensitivity

A new high input impedance filter employing three current feedback amplifiers (CFAs) and six passive elements, three of them are grounded, is presented. The proposed circuit offers the following advantages: simultaneous realization of lowpass (LP), bandpass (BP) and highpass (HP) filtering functions, employs two grounded capacitors, exhibits high input and low output impedances which permits easy cascade connection, low passive sensitivity figures and orthogonal control of resonance frequency (ωo) and bandwidth (ωo/Q). PSPICE simulation results are given to verify the theoretical calculations.

Simulation on the Flow Field of Mini-Hydrocyclones for Different Inlet Sizes

2013 ◽  
Vol 864-867 ◽  
pp. 1183-1191 ◽  
Author(s):  
Chao Yan ◽  
Qiang Yang ◽  
Hua Lin Wang
Keyword(s):  
Aspect Ratio ◽  
Flow Field ◽  
Solid Particles ◽  
Design And Optimization ◽  
Fluent Software ◽  
Simulation Results ◽  
Shape And Size

This paper aims to improve the separation of fine solid particles in mini-hydrocyclones by changing the shape and size of the mini-hydrocyclone inlet. This study also examines the best mini-hydrocyclone inlet shape and size. Fluent software is used to simulate the flow field of the continuous and dispersion phases in different mini-hydrocyclone. The simulation results can guide the design and optimization of mini-hydrocyclones and determine the optimum inlet aspect ratio.

scholarly journals Tri resonance multi slot patch antenna

2020 ◽  
Vol 2 (1) ◽  
pp. 30-37
Author(s):  
Kemal Temur ◽  
Sehabeddin Taha Imeci
Keyword(s):  
Resonance Frequency ◽  
Current Distribution ◽  
Patch Antenna ◽  
Microstrip Patch Antenna ◽  
Simulation Tool ◽  
Microstrip Patch ◽  
Simulation Results

In this work, tri resonance multi slot microstrip patch antenna which operates at three center frequencies of 11 GHz, 11.9 GHz, 15.7 GHz is designed and simulated. As a commercial simulation tool, Sonnet Suites, a planar 3D electromagnetic simulator was used. Details of the simulation results are presented and discussed. As a result, an input match of -6.88 dB at the resonance frequency of 11 GHz, an input match of -37.12 dB at the resonance frequency of 11.9 GHz, an input match of -29.49 dB at the resonance frequency of 15.7 GHz were observed. The gain was observed as 8.25 dB at 11 GHz and 4.82 dB at 11.9 GHz. Also, the gain was observed as 7.07 dB at 15.7 GHz. The patch has several symmetric slots and it’s well known that slots change the current distribution of the patch antenna.

scholarly journals Three dimensional cyclonic turbulent flow structures at various geometries, inlet-outlet orientations and operating conditions

2018 ◽  
Vol 12 (4) ◽  
pp. 4300-4328
Author(s):  
Pasymi Pasymi ◽  
Y. W. Budhi ◽  
A. Irawan ◽  
Y. Bindar
Keyword(s):  
Flow Structure ◽  
Three Dimensional ◽  
Axial Flow ◽  
Operating Conditions ◽  
Flow Structures ◽  
Ansys Fluent ◽  
Vortex Pattern ◽  
Fluent Software ◽  
Simulation Results ◽  
Vortex Patterns

Flow structure inside a chamber greatly determines the process performances. Therefore, the flow structure inside a chamber are often constructed in such a way as an effort to obtain equipment performances in accordance with the expectations. This study explored flow structure inside several chamber geometries and operating conditions. Three types of chamber, namely; GTC, DTC and TJC were set as the investigated chambers. The Computational Fluid Dynamics technique, supported by some experimental data from the literature, is used as an investigation method. The RANS based models, under Ansys-Fluent software were used in this numerical investigation. Simulation results revealed that the flow structures of GTC and DTC are predominantly created by spiral and vortex patterns. The vortex stabilizer diameter in the GTC affects the vortex pattern, velocity profile and pressure drop. The flow structure of DTC presents the most complex behavior. The flow structure inside TJC, in the case of unconfined outlet boundary, is characterized by the helical and wavy jet pattern. This structure is determined by the initial tangential intensity (IIT) and the inlet aspect ratio (RIA). The structures of vortex, helical, and wavy axial flow are properly constructed and visualized in this paper. There is no a turbulence model which is always superior to the other models, consistently. The standard k-ε model exhibits the realistic and robust performances among  all of investigatied cases.

scholarly journals DUAL-BAND RECONFIGURABLE MIMO ANTENNA FOR WIRELESS APPLICATIONS

2021 ◽  
Vol 25 (3) ◽  
pp. 1-9
Author(s):  
Abdullah A. Jabber ◽  
◽  
Raad H. Thaher ◽  
Keyword(s):  
Coupling Effect ◽  
Mimo System ◽  
Dual Band ◽  
Reconfigurable Antenna ◽  
Pin Diode ◽  
Wireless Devices ◽  
Resonant Frequencies ◽  
Mimo Antenna ◽  
Wireless Applications ◽  
Simulation Results

This article presents design and simulation of a new compact four-element dual-band MIMO frequency reconfigurable antenna that can be reconfigured for WiMAX and LTE applications. The antenna includes four elements at the same FR4 substrate with an optimized overall size of 65x65x1.6 mm3 and an optimized partial GND plane of 30x11.125 mm2. The reconfiguration rate is between 2.41 and 3.99 GHz that can cover the WiMAX and LTE wireless devices by applying just one RF (PIN) switch to change the operating frequency. The antenna operates on the two states of the PIN diode under its two states ON and OFF with (2.7 GHz, and 2.8 GHz) resonant frequencies respectively. The proposed antenna produces acceptable simulation results for the MIMO system by achieving gain from (3-7.2) dBi, less than -14.5 dB coupling effect, less than 0.28 envelope correlation coefficient, and diversity gain range from 8.4-10.

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