scholarly journals Experiments and numerical modeling of baffle configuration effects on the performance of sedimentation tanks

2013 ◽  
Vol 40 (2) ◽  
pp. 140-150 ◽  
Author(s):  
A.M. Razmi ◽  
R. Bakhtyar ◽  
B. Firoozabadi ◽  
D.A. Barry
Keyword(s):  
Stokes Equations ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Laboratory Setup ◽  
Advection Diffusion Equation ◽  
Model Predictions ◽  
Empirical Function ◽  
Sedimentation Basins ◽  
Study Laboratory ◽  
Particle Laden Flow

The hydraulic efficiency of sedimentation basins is reduced by short-circuiting, circulation zones and bottom particle-laden jets. Baffles are used to improve the sediment tank performance. In this study, laboratory experiments were used to examine the hydrodynamics of several baffle configurations. An accompanying numerical analysis was performed based on the 2-D Reynolds-averaged Navier–Stokes equations along with the k-ε turbulence closure model. The numerical model was supplemented with the volume-of-fluid technique, and the advection–diffusion equation to simulate the dynamics of particle-laden flow. Model predictions compared well with the experimental data. An empirical function was constructed to indicate the location and amount of sediment collected in the tank. Hydraulic performance was determined for given baffle locations and heights. The results revealed that, for the laboratory setup, a baffle half way along its length decreases its performance, while a baffle much closer to its inlet and with height 25∼30% of water depth improves efficiency.

scholarly journals Comparing fluid mechanics models with experimental data

2003 ◽  
Vol 358 (1437) ◽  
pp. 1567-1576 ◽  
Author(s):  
G. R. Spedding
Keyword(s):  
Fluid Mechanics ◽  
Stokes Equations ◽  
Physical World ◽  
Experimental Models ◽  
Experimental Results ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Dimensionless Groups ◽  
Model Predictions ◽  
Provided Examples

The art of modelling the physical world lies in the appropriate simplification and abstraction of the complete problem. In fluid mechanics, the Navier–Stokes equations provide a model that is valid under most circumstances germane to animal locomotion, but the complexity of solutions provides strong incentive for the development of further, more simplified practical models. When the flow organizes itself so that all shearing motions are collected into localized patches, then various mathematical vortex models have been very successful in predicting and furthering the physical understanding of many flows, particularly in aerodynamics. Experimental models have the significant added convenience that the fluid mechanics can be generated by a real fluid, not a model, provided the appropriate dimensionless groups have similar values. Then, analogous problems can be encountered in making intelligible but independent descriptions of the experimental results. Finally, model predictions and experimental results may be compared if, and only if, numerical estimates of the likely variations in the tested quantities are provided. Examples from recent experimental measurements of wakes behind a fixed wing and behind a bird in free flight are used to illustrate these principles.

A HYBRID FINITE-ANALYTIC ALGORITHM FOR SOLVING THREE-DIMENSIONAL ADVECTION-DIFFUSION EQUATIONS

2004 ◽  
Vol 01 (03) ◽  
pp. 407-430 ◽  
Author(s):  
H. M. HU ◽  
K.-H. WANG
Keyword(s):  
Convergence Rates ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Diffusion Equations ◽  
Staggered Grid ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Advection Diffusion Equation ◽  
Advection Diffusion ◽  
The Stability

The hybrid finite-analytic (HFA) method for discretization of a three-dimensional advection-diffusion equation is developed using the superposition of the HFA solutions of locally linearized one-dimensional advection-diffusion equations. An example calculation of a system of three-dimensional nonlinear equations is conducted to test the convergence and accuracy of the 7-point numerical scheme. Good agreements between calculated and analytical solutions are obtained. An algorithm based on the HFA method with multigrid technique and Gauss-Seidel iteration is also developed to solve the three-dimensional Navier-Stokes equations in a staggered grid system. The stability and efficiency of the method are demonstrated by performing calculations of the fluid flow in a three-dimensional cubic cavity with a moving top wall. The proposed procedure is observed to exhibit good rates of smoothing and almost grid-independent convergence rates in comparison with a single-grid iteration method. The results are in excellent agreement with other published computational results.

Prediction of Cascade Flow Fields Using the Averaged Navier-Stokes Equations

1984 ◽  
Vol 106 (2) ◽  
pp. 383-390 ◽  
Author(s):  
S. J. Shamroth ◽  
H. McDonald ◽  
W. R. Briley
Keyword(s):  
Transonic Flow ◽  
Static Pressure ◽  
Stokes Equations ◽  
Solution Procedure ◽  
Navier Stokes ◽  
Compressor Cascade ◽  
Navier Stokes Equations ◽  
Cascade Flow ◽  
Model Predictions ◽  
Flow Through

A numerical solution procedure for the ensemble-averaged, compressible, time-dependent Navier-Stokes equations is applied to predict the flow about a cascade of airfoils operating in the transonic flow regime. The equations are solved by the consistently split, linearized block implicit (LBI) method of Briley and McDonald. Boundary conditions are set so as to specify upstream total pressure and downstream static pressure. Turbulence is modeled by a mixing length model. Predictions are made for flow through a compressor cascade configuration. The method yields converged solutions within a relatively small number of time steps ( ≈ 150), which give good comparisons with experimental data.

scholarly journals Application of a Navier-Stokes Analysis to Transonic Cascade Flow Fields

1982 ◽  
Author(s):  
S. J. Shamroth ◽  
H. McDonald ◽  
W. R. Briley
Keyword(s):  
Flow Field ◽  
Stokes Equations ◽  
Solution Procedure ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Controlled Diffusion ◽  
Cascade Flow ◽  
Model Predictions ◽  
Flow Through ◽  
Transonic Cascade

A numerical solution procedure for the ensemble-averaged compressible time-dependent Navier-Stokes equations is applied to the transonic cascade flow field. The equations are solved by the consistently split linearized block implicit (LBI) method of Briley and McDonald. Boundary conditions are set so as to specify upstream total pressure and downstream static pressure. Turbulence is modeled by a mixing length model. Predictions are made for flow through a Jose Sanz controlled diffusion cascade and the method yields converged solutions within a relatively small number of time steps (≈ 150). Although to date comparisons with data have not been made, the results show the expected cascade flow field features.

Effects of stator splitter blades on aerodynamic performance of a single-stage transonic axial compressor

2020 ◽  
Vol 14 (4) ◽  
pp. 7369-7378
Author(s):  
Ky-Quang Pham ◽  
Xuan-Truong Le ◽  
Cong-Truong Dinh
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Aerodynamic Performance ◽  
Numerical Results ◽  
Single Stage ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Operating Stability ◽  
Length Coverage

Splitter blades located between stator blades in a single-stage axial compressor were proposed and investigated in this work to find their effects on aerodynamic performance and operating stability. Aerodynamic performance of the compressor was evaluated using three-dimensional Reynolds-averaged Navier-Stokes equations using the k-e turbulence model with a scalable wall function. The numerical results for the typical performance parameters without stator splitter blades were validated in comparison with experimental data. The numerical results of a parametric study using four geometric parameters (chord length, coverage angle, height and position) of the stator splitter blades showed that the operational stability of the single-stage axial compressor enhances remarkably using the stator splitter blades. The splitters were effective in suppressing flow separation in the stator domain of the compressor at near-stall condition which affects considerably the aerodynamic performance of the compressor.

Sensitivity analysis for Navier-Stokes equations on unstructured meshes using complex variables

AIAA Journal ◽  
2001 ◽  
Vol 39 ◽  
pp. 56-63
Author(s):  
W. Kyle Anderson ◽  
James C. Newman ◽  
David L. Whitfield ◽  
Eric J. Nielsen
Keyword(s):  
Sensitivity Analysis ◽  
Stokes Equations ◽  
Unstructured Meshes ◽  
Complex Variables ◽  
Navier Stokes ◽  
Navier Stokes Equations

Numerical solution of the reduced Navier-Stokes equations for internal incompressible flows

AIAA Journal ◽  
2000 ◽  
Vol 38 ◽  
pp. 1603-1614
Author(s):  
Martin Scholtysik ◽  
Bernhard Mueller ◽  
Torstein K. Fannelop
Keyword(s):  
Numerical Solution ◽  
Incompressible Flows ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Navier Stokes Equations
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