Turbulent Flow
Pressure Drop Along Pipe Length – Turbulent
Problem Statement: 3D turbulent flow in a straight pipe is modeled using the standard k-ε turbulence model.
References: F.M. White. Fluid Mechanics. 3rd Edition. McGraw Hill Book Co. Inc., New York, NY, 1994.
Fluid Properties
Geometric Properties
Working Conditions
Density = 1.225 kg/m3
Viscosity = 1.7894e-5 Pa-s
Radius = 0.002 m
Length = 2 m
Inlet Velocity = 50m/s
Outlet Pressure = 0 Pa
Result Comparison
Results
Analytical
Creo Flow Analysis
% Difference
Pressure Drop (Pa)
0.743
0.73
0.48
Transonic Flow Over an Airfoil RAE2822
Problem Statement: 2D transonic flow is modeled around an airfoil RAE2822 under wind tunnel conditions using the standard k-ε turbulence model.
Chord Length = 1 m
References: P.H. Cook, M.A. McDonald, M.C.P. Firmin. “Aerofoil RAE 2822 - Pressure Distributions, and Boundary Layer and Wake Measurements.” AGARD Advisory Report No. 138.
Fluid Properties
Geometric Properties
Working Conditions
Air
Density = Ideal Gas Law
Viscosity= 3.54822 X 10 -5 kg/ ms
RAE 2822 Airfoil
AoA = 2.31 deg
Wind tunnel height = 72 m
Wind tunnel length = 96 m
M = 0.729
Pressure at boundaries = 71154 Pa
Temperature at boundaries = 271 K
Result – Pressure contours around airfoil
Result Comparison – Lift and drag coefficients
Results
Target
Creo Flow Analysis
Percent Error
Lift Coefficient
0.743
0.73
1.75
Drag Coefficient
0.0127
0.0126
0.79
Result Comparison – Coefficient of pressure distribution
Turbulent Flow Over A Backwards Facing Step
Problem Statement: 2-D turbulent flow with separation and reattachment is modeled for a backwards facing step with the Renormalization Group k-ε model.
A = Inlet
B = Step
C = Outlet
References: D.M. Driver, H.L. Seegmiller, "Features of a Reattaching Turbulent Shear Layer in Divergent Channel Flow". AIAA Journal,Vol 23, pp. 163-171, 1985.
Fluid Properties
Geometric Properties
Working Conditions
Density: 1 kg/m3
Viscosity: 0.0001 kg/m-s
Step height = 1 m
Length of the channel = 34 m
Height of the channel = 9 m
Inlet: Fully developed velocity profile at 3.74 m/s
Outlet: Atmospheric pressure
Result Comparison – Reattachment length
The reattachment length is the distance from the step at which the flow resumes in the positive flow direction. The experiment provides a range for the reattachment length.
Reattachment Length
Experiment
Creo Flow Analysis
x/H = 6.16 – 6.34
x/H = 6.21
Result Comparison – Skin friction coefficient
Prediction of the reattachment point downstream of the step was determined in the experiment by the following:
Laser oil-flow interferometer measurements of skin-friction
Interpolation of the zero skin-friction location. The experimental and the CFD results along the wall are compared below.
Vortex Shedding Over A Cylinder
Problem Statement: Flow over a cylinder is modeled using the standard k- ε turbulence model.
References: Williamson, C. H. K. (1988). Defining a universal and continuous Strouhal–Reynolds number relationship for the laminar vortex shedding of a circular cylinder. Physics of Fluids.
Fluid Properties
Geometric Properties
Working Conditions
Density=1 kg/m3
Viscosity= 0.01 Pa-s
See Image Above
Transient = 0.01 s
Inlet velocity = 1m/s
Outlet pressure = 0 Pa
Results – z-Vorticity after 150 s
Result Comparison – Strouhal number
The Strouhal number measures the shedding frequency.
Result
Target
Creo Flow Analysis
% Difference
Strouhal Number
0.164
0.165
0.61
Transitional Recirculatory Flow Inside a Ventilation Enclosure
Problem Statement: 3D recirculatory flow is modeled in a ventilation enclosure using the standard k-ε model.
I = Inlet
O = Outlet
References: P.V. Nielsen, A Restivo, J.H. Whitelaw, “The Velocity Characteristics of Ventilated Rooms”, Journal of Fluids Engineering, Vol 100, pp.291-298 , 1978.
Fluid Properties
Geometric Properties
Working Conditions
Density = 1.1766 kg/m3
Viscosity = 1.853e-5 Pa-s
L = 267.9 mm
W = 89.3 mm
Inlet height = 5 mm
Outlet height = 14.3 mm
Inlet velocity = 15.78 m/s
Outlet pressure = Atmospheric
Results – X-Velocity contours at centerline
Results – Y-Velocity contours at centerline
Result Comparison – Normalized velocity along the y-direction of the enclosure
Turbulent Flow in a Diffuser
Problem Statement: 3D turbulent flow in a diffuser is modeled using the standard k- ε turbulence model.
References: Azad, R. S., & Kassab, S. Z. (1989). Turbulent flow in a conical diffuser: Overview and implications. Physics of Fluids A: Fluid Dynamics, 1(3), 564–573.
Fluid Properties
Geometric Properties
Working Conditions
Density = 1.15758 kg/m3
Viscosity = 1.8406 x 10-5 Pa-s
See Image Above
Inlet velocity = 18.06 m/s
Outlet pressure = 0 Pa
Results – Pressure contours
Results Comparison – Coefficient of pressure along diffuser wall
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