Unsteady Laminar Duct Flow With a Given Volume Flow Rate Variation

1999 ◽  
Vol 67 (2) ◽  
pp. 274-281 ◽  
Author(s):  
D. Das ◽  
J. H. Arakeri
Keyword(s):  
Cross Section ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Circular Cross Section ◽  
Volume Flow ◽  
Rate Variation ◽  
Two Dimensional ◽  
Duct Flow ◽  
Fully Developed Flow ◽  
Gradient Variation

In this paper we give a procedure to obtain analytical solutions for unsteady laminar flow in an infinitely long pipe with circular cross section, and in an infinitely long two-dimensional channel, created by an arbitrary but given volume flow rate with time. In the literature, solutions have been reported when the pressure gradient variation with time is prescribed but not when the volume flow rate variation is. We present some examples: (a) the flow rate has a trapezoidal variation with time, (b) impulsively started flow, (c) fully developed flow in a pipe is impulsively blocked, and (d) starting from rest the volume flow rate oscillates sinusoidally. [S0021-8936(00)01702-5]

Numerical Simulation and Optimal Design Investigation on Air Duct of Floor Standing Air-Conditioner

2011 ◽  
Vol 308-310 ◽  
pp. 563-567
Author(s):  
Zhong Min Wan ◽  
Zu Yi Zheng ◽  
Huan Xin Chen ◽  
Jun Liu ◽  
Ting Xiang Jin
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Aerodynamic Characteristic ◽  
Volume Flow Rate ◽  
Structural Characteristics ◽  
Flow Characteristics ◽  
Volume Flow ◽  
Numerical Results ◽  
Air Conditioner ◽  
Duct Flow

According to the structural characteristics of floor standing air-conditioner，three dimensional numerical model of air duct system for a certain floor standing air-conditioner is developed to simulate aerodynamic characteristic of the air duct. Flow characteristics and deficiency of air duct for original floor standing air-conditioner are analyzed, and the optimal schemes of air duct are raised and numerical simulation has been carried on to obtain aerodynamic characteristic of the new air duct. The numerical results show that the volume flow rate of air-conditioner with new air duct is increased by 6.1%. The experimental results of air-conditioner with new air duct show the volume flow rate of new air duct is promoted by 5.6% at the same approximate noise level. The numerical results agree well with the previous experiment.

scholarly journals Unsteady Unidirectional Flow of Second-Grade Fluid through a Microtube with Wall Slip and Different Given Volume Flow Rate

2010 ◽  
Vol 2010 ◽  
pp. 1-17 ◽  
Author(s):  
Cha'o-Kuang Chen ◽  
Hsin-Yi Lai ◽  
Wei-Fan Chen
Keyword(s):  
Flow Rate ◽  
Volume Flow Rate ◽  
Wall Slip ◽  
Volume Flow ◽  
Second Grade ◽  
Fully Developed Flow ◽  
Unidirectional Flow ◽  
Laplace Transform Technique ◽  
Grade Fluid ◽  
Flow Through

The second-grade flows through a microtube with wall slip are solved by Laplace transform technique. The effects of rarefaction and elastic coefficient are considered with an unsteady flow through a microtube for a given but arbitrary inlet volume flow rate with time. Five cases of inlet volume flow rate are as follows: (1) trapezoidal piston motion, (2) constant acceleration, (3) impulsively started flow, (4) impulsively blocked fully developed flow, and (5) oscillatory flow. The results obtained are compared to those solutions under no-slip and slip condition.

Notizen: Strömung von nematischen Flüssigkristallen in Kapillaren mit rechteckigem Querschnitt /The Flow of an Nematic Liquid Crystal in a Capillary with a Rectangular Cross Section

1980 ◽  
Vol 35 (12) ◽  
pp. 1426-1428 ◽  
Author(s):  
F. Schneider
Keyword(s):  
Liquid Crystal ◽  
Velocity Profile ◽  
Cross Section ◽  
Nematic Liquid Crystal ◽  
Flow Rate ◽  
Rectangular Cross Section ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Viscosity Coefficients

Abstract The velocity profile for the flow of an incompressible nematic liquid crystal in a capillary with a rectangular cross section is calculated. Equations for the determination of the different viscosity coefficients from the volume flow rate and the pressure difference are presented.

Analysis of Unsteady Flow Through a Microtube With Wall Slip and Given Inlet Volume Flow Rate Variations

2008 ◽  
Vol 75 (1) ◽  
Author(s):  
Chun-I Chen ◽  
Cha’o-Kuang Chen ◽  
Heng-Ju Lin
Keyword(s):  
Unsteady Flow ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Wall Slip ◽  
Volume Flow ◽  
Fully Developed Flow ◽  
Potential Core ◽  
Analysis Process ◽  
Flow Through ◽  
Trapezoidal Piston Motion

This study examines the effects of rarefaction of an unsteady flow through a microtube for a given but arbitrary inlet volume flow rate. Four cases of inlet volume flow rate proposed by Das and Arakeri (2000, ASME J. Appl. Mech., 67, pp. 274–281) are as follows: (1) trapezoidal piston motion, (2) constant acceleration, (3) impulsively started flow, and (4) impulsively blocked fully developed flow. During the analysis process, the Knudsen number (Kn) is used to represent the degree of rarefaction. The analytical results are presented graphically and compared to the results for a continuum under a no-slip condition. The effect of wall-slip became significant with the increasing degrees of rarefaction. The velocity in the boundary layer increased, whereas the velocity in the potential core of the microtube decreased, under the same condition. The influence of the rarefaction for the pressure gradient varied for the four cases.

Novel epoxy/anhydride alternatives for biological electron microscopy: Physical and performance characteristis of embed 812 and LX 112 in combination with NSA/NMA/DMAE

1989 ◽  
Vol 47 ◽  
pp. 1000-1001
Author(s):  
Joe A. Mascorro ◽  
Gerald S. Kirby
Keyword(s):  
Electron Microscopy ◽  
Flow Rate ◽  
Succinic Anhydride ◽  
Volume Flow Rate ◽  
Mass Density ◽  
Uranyl Acetate ◽  
Volume Flow ◽  
Base Resin ◽  
And Performance ◽  
Acid Anhydrides

Embedding media based upon an epoxy resin of choice and the acid anhydrides dodecenyl succinic anhydride (DDSA), nadic methyl anhydride (NMA), and catalyzed by the tertiary amine 2,4,6-Tri(dimethylaminomethyl) phenol (DMP-30) are widely used in biological electron microscopy. These media possess a viscosity character that can impair tissue infiltration, particularly if original Epon 812 is utilized as the base resin. Other resins that are considerably less viscous than Epon 812 now are available as replacements. Likewise, nonenyl succinic anhydride (NSA) and dimethylaminoethanol (DMAE) are more fluid than their counterparts DDSA and DMP- 30 commonly used in earlier formulations. This work utilizes novel epoxy and anhydride combinations in order to produce embedding media with desirable flow rate and viscosity parameters that, in turn, would allow the medium to optimally infiltrate tissues. Specifically, embeding media based on EmBed 812 or LX 112 with NSA (in place of DDSA) and DMAE (replacing DMP-30), with NMA remaining constant, are formulated and offered as alternatives for routine biological work.Individual epoxy resins (Table I) or complete embedding media (Tables II-III) were tested for flow rate and viscosity. The novel media were further examined for their ability to infilftrate tissues, polymerize, sectioning and staining character, as well as strength and stability to the electron beam and column vacuum. For physical comparisons, a volume (9 ml) of either resin or media was aspirated into a capillary viscocimeter oriented vertically. The material was then allowed to flow out freely under the influence of gravity and the flow time necessary for the volume to exit was recored (Col B,C; Tables). In addition, the volume flow rate (ml flowing/second; Col D, Tables) was measured. Viscosity (n) could then be determined by using the Hagen-Poiseville relation for laminar flow, n = c.p/Q, where c = a geometric constant from an instrument calibration with water, p = mass density, and Q = volume flow rate. Mass weight and density of the materials were determined as well (Col F,G; Tables). Infiltration schedules utilized were short (1/2 hr 1:1, 3 hrs full resin), intermediate (1/2 hr 1:1, 6 hrs full resin) , or long (1/2 hr 1:1, 6 hrs full resin) in total time. Polymerization schedules ranging from 15 hrs (overnight) through 24, 36, or 48 hrs were tested. Sections demonstrating gold interference colors were collected on unsupported 200- 300 mesh grids and stained sequentially with uranyl acetate and lead citrate.

Multi-objective optimization of squirrel cage fan for range hood based on Kriging model

2021 ◽  
pp. 095440622199586
Author(s):  
Qianhao Xiao ◽  
Jun Wang ◽  
Boyan Jiang ◽  
Weigang Yang ◽  
Xiaopei Yang
Keyword(s):  
Flow Rate ◽  
Optimization Design ◽  
Volume Flow Rate ◽  
Kriging Model ◽  
Volume Flow ◽  
Design Parameters ◽  
Multi Objective Optimization ◽  
Nsga Ii ◽  
Multi Objective ◽  
Squirrel Cage

In view of the multi-objective optimization design of the squirrel cage fan for the range hood, a blade parameterization method based on the quadratic non-uniform B-spline (NUBS) determined by four control points was proposed to control the outlet angle, chord length and maximum camber of the blade. Morris-Mitchell criteria were used to obtain the optimal Latin hypercube sample based on the evolutionary operation, and different subsets of sample numbers were created to study the influence of sample numbers on the multi-objective optimization results. The Kriging model, which can accurately reflect the response relationship between design variables and optimization objectives, was established. The second-generation Non-dominated Sorting Genetic algorithm (NSGA-II) was used to optimize the volume flow rate at the best efficiency point (BEP) and the maximum volume flow rate point (MVP). The results show that the design parameters corresponding to the optimization results under different sample numbers are not the same, and the fluctuation range of the optimal design parameters is related to the influence of the design parameters on the optimization objectives. Compared with the prototype, the optimized impeller increases the radial velocity of the impeller outlet, reduces the flow loss in the volute, and increases the diffusion capacity, which improves the volume flow rate, and efficiency of the range hood system under multiple working conditions.

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