A Viscous-Inviscid Interaction Procedure—Part 2: Application to Turbulent Flow Over a Rearward-Facing Step

1986 ◽  
Vol 108 (1) ◽  
pp. 71-75 ◽  
Author(s):  
O. K. Kwon ◽  
R. H. Pletcher
Keyword(s):  
Turbulent Flow ◽  
Turbulence Modeling ◽  
Numerical Procedure ◽  
Length Scale ◽  
Two Dimensional ◽  
Reattachment Length ◽  
Mean Flow ◽  
Channel Expansion ◽  
Good Agreement

The viscous-inviscid interaction numerical procedure described in Part 1 is used to predict steady, two-dimensional turbulent flow over a rearward-facing step. The accuracy of predictions is observed to be quite sensitive to the specification of length scale in the turbulence modeling. The best results are observed when the length scale is specified algebraically downstream of the step using parameters characteristic of the step geometry. Predictions of mean flow quantities and reattachment length are shown to be in generally good agreement with measurements obtained over a range of channel expansion ratios.

The dispersion of matter in turbulent flow through a pipe

1954 ◽  
Vol 223 (1155) ◽  
pp. 446-468 ◽  
Keyword(s):  
Turbulent Flow ◽  
Capillary Tube ◽  
Resistance Coefficient ◽  
Mean Flow ◽  
Combined Action ◽  
Flow Through ◽  
The Mean ◽  
Coefficient Of Diffusion ◽  
Good Agreement ◽  
Made In

The dispersion of soluble matter introduced into a slow stream of solvent in a capillary tube can be described by means of a virtual coefficient of diffusion (Taylor 1953 a ) which represents the combined action of variation of velocity over the cross-section of the tube and molecluar diffusion in a radial direction. The analogous problem of dispersion in turbulent flow can be solved in the same way. In that case the virtual coefficient of diffusion K is found to be 10∙1 av * or K = 7∙14 aU √ γ . Here a is the radius of the pipe, U is the mean flow velocity, γ is the resistance coefficient and v * ‘friction velocity’. Experiments are described in which brine was injected into a straight 3/8 in. pipe and the conductivity recorded at a point downstream. The theoretical prediction was verified with both smooth and very rough pipes. A small amount of curvature was found to increase the dispersion greatly. When a fluid is forced into a pipe already full of another fluid with which it can mix, the interface spreads through a length S as it passes down the pipe. When the interface has moved through a distance X , theory leads to the formula S 2 = 437 aX ( v * / U ). Good agreement is found when this prediction is compared with experiments made in long pipe lines in America.

Turbulent Flow Around a Bluff Rectangular Plate. Part II: Numerical Predictions

1991 ◽  
Vol 113 (1) ◽  
pp. 60-67 ◽  
Author(s):  
N. Djilali ◽  
I. S. Gartshore ◽  
M. Salcudean
Keyword(s):  
Rectangular Plate ◽  
Marked Improvement ◽  
Separation Bubble ◽  
Reattachment Length ◽  
Mean Flow ◽  
Discretization Methods ◽  
Streamline Curvature ◽  
Pressure Distributions ◽  
Numerical Predictions ◽  
Good Agreement

This paper presents calculations of the time-averaged separated-reattaching flow around a bluff rectangular plate, using a finite difference procedure and the k-ε turbulence model. Two discretization methods are used: the hybrid differencing scheme, and the bounded skew hybrid differencing scheme. The latter, although superior to the former for all grid distributions, results in a reattachment length about 30 percent shorter than the measured value. When a modification which takes into account streamline curvature is incorporated into the k-ε model, a marked improvement in the predictions is obtained. A reattachment length of 4.3 plate thicknesses (D), compared to an experimental value of 4.7D, is obtained, and the predicted mean flow field, turbulent kinetic energy and pressure distributions within the separation bubble are found to be in good agreement with experiments.

scholarly journals Numerical Analysis of Turbulent Flow Around Two-Dimensional Bodies Using Non-Orthogonal Body-Fitted Mesh

2019 ◽  
Vol 24 (2) ◽  
pp. 387-410
Author(s):  
Md. Shahjada Tarafder ◽  
M. Al Mursaline
Keyword(s):  
Turbulent Flow ◽  
Computational Cost ◽  
Numerical Procedure ◽  
Simple Algorithm ◽  
Two Dimensional ◽  
Governing Equations ◽  
Wall Functions ◽  
Relaxation Factors ◽  
Volume Method ◽  
Naca 0012

Abstract This paper deals with the numerical simulation of a turbulent flow around two-dimensional bodies by the finite volume method with non-orthogonal body-fitted grid. The governing equations are expressed in Cartesian velocity components and solution is carried out using the SIMPLE algorithm for collocated arrangement of scalar and vector variables. Turbulence is modeled by the k- ε turbulence model and wall functions are used to bridge the solution variables at the near wall cells and the corresponding quantities on the wall. A simplified pressure correction equation is derived and proper under-relaxation factors are used so that computational cost is reduced without adversely affecting the convergence rate. The numerical procedure is validated by comparing the computed pressure distribution on the surface of NACA 0012 and NACA 4412 hydrofoils for different angles of attack with experimental data. The grid dependency of the solution is studied by varying the number of cells of the C-type structured mesh. The computed lift coefficients of NACA 4412 hydrofoil at different angles of attack are also compared with experimental results to further substantiate the validity of the proposed methodology.

scholarly journals Incompressible Turbulent Flow Simulation Using theκ-ɛModel and Upwind Schemes

2007 ◽  
Vol 2007 ◽  
pp. 1-26 ◽  
Author(s):  
V. G. Ferreira ◽  
A. C. Brandi ◽  
F. A. Kurokawa ◽  
P. Seleghim Jr. ◽  
A. Castelo ◽  
...  
Keyword(s):  
Free Surface ◽  
Turbulent Flow ◽  
Turbulent Flows ◽  
Turbulence Modeling ◽  
Numerical Technique ◽  
Numerical Procedure ◽  
Flow Simulation ◽  
Wall Functions ◽  
Upwind Schemes ◽  
High Reynolds

In the computation of turbulent flows via turbulence modeling, the treatment of the convective terms is a key issue. In the present work, we present a numerical technique for simulating two-dimensional incompressible turbulent flows. In particular, the performance of the high Reynoldsκ-ɛmodel and a new high-order upwind scheme (adaptative QUICKEST by Kaibara et al. (2005)) is assessed for 2D confined and free-surface incompressible turbulent flows. The model equations are solved with the fractional-step projection method in primitive variables. Solutions are obtained by using an adaptation of the front tracking GENSMAC (Tomé and McKee (1994)) methodology for calculating fluid flows at high Reynolds numbers. The calculations are performed by using the 2D version of theFreeflowsimulation system (Castello et al. (2000)). A specific way of implementing wall functions is also tested and assessed. The numerical procedure is tested by solving three fluid flow problems, namely, turbulent flow over a backward-facing step, turbulent boundary layer over a flat plate under zero-pressure gradients, and a turbulent free jet impinging onto a flat surface. The numerical method is then applied to solve the flow of a horizontal jet penetrating a quiescent fluid from an entry port beneath the free surface.

Prediction of Recirculating, Swirling, Turbulent Flow in Rotating Disc Systems

1976 ◽  
Vol 18 (3) ◽  
pp. 142-148 ◽  
Author(s):  
A. D. Gosman ◽  
F. C. Lockwood ◽  
J. N. Loughhead
Keyword(s):  
Experimental Data ◽  
Finite Difference ◽  
Turbulent Flow ◽  
Turbulent Transport ◽  
Transport Processes ◽  
Two Dimensional ◽  
Rotating Disc ◽  
Rigorous Testing ◽  
Source Flow ◽  
Good Agreement

Predictions were made of the swirling, recirculating, turbulent flow between a rotating and a stationary shrouded disc with an axial source flow. A two-dimensional finite-difference procedure was used. Turbulent transport processes were calculated with the aid of a turbulence model involving the solution of two differential equations. Comparison of predicted disc torque with experimental data showed good agreement. Details of the predicted flow between the discs are presented and shown to be plausible; they also highlight the need for detailed hydrodynamic measurements in these types of flows to aid more rigorous testing of the method.

Blockage Effects on Two-dimensional Bluff Body Flow

1975 ◽  
Vol 26 (4) ◽  
pp. 243-253 ◽  
Author(s):  
J E Fackrell
Keyword(s):  
Flow Field ◽  
Strouhal Number ◽  
Bluff Body ◽  
The Body ◽  
Base Pressure ◽  
Two Dimensional ◽  
Mean Flow ◽  
Free Air ◽  
Bluff Body Flow ◽  
Good Agreement

SummaryThe time mean flow past a two-dimensional bluff body in a wind-tunnel is modelled by an adaptation of the numerical free-streamline method of Bearman and Fackrell. Provided the base pressure and separation positions are specified in advance, the method allows the calculation of the flow field outside the wake and in particular of the pressures on the wetted surface of the body. Good agreement of the predicted pressures with experimental results is obtained for a flat plate, wedge and circular cylinder at various blockage ratios. In addition to predicting the confined flow, it is shown that a free-air base pressure can be simply deduced from the confined base pressure. With an assumption that the separation positions are unaffected by blockage, this allows the free-air flow field to be calculated. By using an analogy to Roshko’s Strouhal number, which has been found to be invariant under constraint, a free-air Strouhal number can also be deduced.

Computation of Annular, Turbulent Flow With Rotating Core Tube

1976 ◽  
Vol 98 (4) ◽  
pp. 753-758 ◽  
Author(s):  
B. I. Sharma ◽  
B. E. Launder ◽  
C. J. Scott
Keyword(s):  
Experimental Data ◽  
Turbulent Flow ◽  
Transport Model ◽  
Rotational Velocity ◽  
Numerical Procedure ◽  
Mean Flow ◽  
Core Tube ◽  
The Core ◽  
Numerical Predictions ◽  
Bulk Flow Rate

Numerical predictions are presented of fully-developed turbulent flow through a concentric annulus in which the core tube rotates about its axis. Comparisons are drawn with the extensive experimental data of Kuzay and Scott [1] which span Reynolds numbers from 1.7 to 104 to 6.5 × 104 and with rotational speeds of the core tube varying from zero to nearly 2.8 times the bulk axial velocity. Predictions have been obtained by means of an adapted version of the Patankar-Spalding [5], numerical procedure employing, as turbulent transport model, the version of the mixing length hypothesis applied by Koosinlin, Sharma and Launder [2] to flows on spinning cones and cylinders. Agreement with experiment is generally close at the higher relative swirl rates but the predictions of the swirling velocity profile deteriorate as the bulk flow rate is increased. The discrepancy seems to be due to the experimental data requiring a greater development length as the magnitude of the rotational velocity is reduced relative to that of the mean flow. Demonstrative developing-flow predictions are provided which exhibit closer agreement with the experimental data.

Analysis of Frost Growth through a Two-Dimensional Duct with Turbulent Flow

2008 ◽  
Vol 39 (4) ◽  
pp. 347-370
Author(s):  
M. Salmanpour ◽  
O. Nourani Zonouz ◽  
Mahmood Yaghoubi
Keyword(s):  
Turbulent Flow ◽  
Two Dimensional ◽  
Frost Growth

scholarly journals Nonlinear two-dimensional free surface solutions of flow exiting a pipe and impacting a wedge

2021 ◽  
Vol 126 (1) ◽  
Author(s):  
Alex Doak ◽  
Jean-Marc Vanden-Broeck
Keyword(s):  
Surface Tension ◽  
Integral Equation ◽  
Free Surface ◽  
Boundary Integral ◽  
Boundary Integral Method ◽  
Two Dimensional ◽  
Numerical Schemes ◽  
Additional Advantage ◽  
Infinite Wedge ◽  
Good Agreement

AbstractThis paper concerns the flow of fluid exiting a two-dimensional pipe and impacting an infinite wedge. Where the flow leaves the pipe there is a free surface between the fluid and a passive gas. The model is a generalisation of both plane bubbles and flow impacting a flat plate. In the absence of gravity and surface tension, an exact free streamline solution is derived. We also construct two numerical schemes to compute solutions with the inclusion of surface tension and gravity. The first method involves mapping the flow to the lower half-plane, where an integral equation concerning only boundary values is derived. This integral equation is solved numerically. The second method involves conformally mapping the flow domain onto a unit disc in the s-plane. The unknowns are then expressed as a power series in s. The series is truncated, and the coefficients are solved numerically. The boundary integral method has the additional advantage that it allows for solutions with waves in the far-field, as discussed later. Good agreement between the two numerical methods and the exact free streamline solution provides a check on the numerical schemes.

Level set-based topology optimization for two dimensional turbulent flow using an immersed boundary method

2021 ◽  
pp. 110630
Author(s):  
Seiji Kubo ◽  
Atsushi Koguchi ◽  
Kentaro Yaji ◽  
Takayuki Yamada ◽  
Kazuhiro Izui ◽  
...  
Keyword(s):  
Topology Optimization ◽  
Turbulent Flow ◽  
Level Set ◽  
Immersed Boundary Method ◽  
Immersed Boundary ◽  
Two Dimensional ◽  
Boundary Method
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