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FloEFD Validation Examples
Your Initials, Presentation Title, Month Year
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FloEFD Validation and Software Test Matrix
Before the release of each version of FloEFD a suite of 300 test cases are run through the different CAD embedded versions of the software
The test matrix ranges from simple 2D tests to industrial scale 3D benchmarks (see the following slides for a sample set of FloEFD validations)
The validation suite includes many classical CFD benchmark cases including a wide range of flow turbulence scenarios and regimes suitable for a General Purpose CFD code
The following slides illustrate some of the benchmarks each FloEFD release has to meet.
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X/LR
separationstreamlines,calculation
vortexcenter,calculation
Resistance
Velocity profiles
Recirculation zone
FloEFD Validation: Flow in 2D Channels with bilateral and unilateral expansions (Backward Facing Steps)
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1Idelchik, I.E., Handbook of Hydraulic Resistance.
2nd ed., McGraw Hill, New York, 1979
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EFD.Lab
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2Yanshin, B.I.: Hydrodynamic Characteristics of Pipeline Valves and Elements.
Convergen Sections, Divergent Sections and Valves. “Mashinostroenie”, Moscow, 1965
FloEFD
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T VX VY Streamlines
Nusselt number vs. Rayleigh number
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Nuav
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Ref.12
EFD.Lab
FloEFD Validation: Natural Convection in a Square Cavity
Dimensionless Velocities vs. Rayleigh Number
References10 Davis, G. De Vahl; Jones, I.P.: Natural Convection in a Square Cavity: a Comparison Exercise. Int. J. for Num. Meth. In Fluids, v.3, pp. 227-248 (1983)11 Emery, A., Chu, T.Y.: Heat Transfer across Vertical Layers. J. Heat Transfer, v. 87, p. 110 (1965)12 Denham, M.K., Patrick M.A.: Laminar Flow over a Downstream Facing Step in a Two-Dimensional Flow Channel. Trans. Instn. Chem. Engrs., v. 52, pp. 361-367 (1974)
FloEFD
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FloEFD Validation: Couette Flow between Parallel Flat Plates at Re = 3.4 x 104
A classical plane flow is one between two parallel infinite flat plates spaced at a distance h from one another and moving at velocity U in opposite directions ,
Dimensionless velocity profiles for different meshes (10, 20, 40, 80 mesh cells across the channel) compare well with experimental data illustrating that with relatively coarse meshes good predictions can be expected when using FloEFD.
h
y
x
u(y)
U
-U
-1,0
-0,8
-0,6
-0,4
-0,2
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1,0
-1,0 -0,8 -0,6 -0,4 -0,2 0,0 0,2 0,4 0,6 0,8 1,0
u/U
y/(h/2)
experiment (Ref.9)
FloEFD, 10 cells
FloEFD, 20 cells
FloEFD, 40 cells
FloEFD, 80 cells
References
1. Schlichting, H. Boundary-Layer Theory. McGraw-Hill, New York, 1979.
1)
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Sh
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1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06
ReD
NuD Calculation, steady-state
Calculation, time-dependent
Flow Trajectories over and past a Circular Cylinder at Re=41:Qualitative Comparison with Experiment (Ref 9)
Strouhal Number vs. Reynolds Number (Ref 4) Drag Coefficient vs. Reynolds Number (Ref 3)
Nusselt Number vs. Reynolds Number(Ref 6)
FloEFD Validation: Flow and Heat Transfer over a Circular Cylinder for Low Reynolds Numbers
References3. Panton, R.L., Incompressible Flow. 2nd ed., John Wiley & Sons, Inc., 19964. White, F.M., Fluid Mechanics. 3rd ed., McGraw-Hill, New York, 19946. Holman, J.P., Heat Transfer. 8th ed., McGraw-Hill, New York, 19979. Davis, G. De Vahl: Natural Convection of Air in a Square Cavity: a Bench Mark Numerical Solution. Int. J. for Num. Meth. In Fluids, v. 3, pp. 249-264 (1983)
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FloEFD Validation: Unsteady Vortex Shedding Flow over a Circular Cylinder at Re=3.7x105
Mesh Density
(cells per cylinder
diameter)
Deviation from
experimental data
(%)
FloEFD, 20 cells per
diameter0.82 -18 650
FloEFD, 40 cells per
diameter0.95 -5 330
FloEFD, 80 cells per
diameter1.02 2 170
Experiment (Driver
and Seegmiller 1985)1.0 n/a n/a
a) b)
c) d)
dC
maxy
Driver, D.M. and Seegmiller, H.L. (1985).
Features of a Reattaching Turbulent Shear
Layer in Divergent Channel Flow. AIAA Journal,
Vol. 23, p. 163.
Predicted turbulent transient flow
velocity fields over a circular
cylinder calculated with FloEFD
for different computational
meshes having:
a) 20 quad cells per diameter, b) 40 quad cells per diameter,c) 80 quad cells per diameter, &d) Similar real flow shadowgraph from
Driver and Seegmiller (1985)
Circular cylinder drag coefficients
calculated with FloEFD in
comparison with experimental
data (Driver and Seegmiller
1985).
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Mach number distribution
Classical benchmark of air flow at inlet M=3 in a 2D (planar) convergent-divergent channel
FloEFD Validation: Supersonic Flow in a 2-D Convergent-Divergent Channel
ReferencePoint
1 2 3 4 5
X ordinate (m) 0.0042 0.047 0.1094 0.155 0.1648
Y ordinate (m) 0.0175 0.0157 0.026 0.026 0.0157
Mach Number (Theory)
3.000 2.427 1.957 2.089 2.365
Mach Number(FloEFD)
3.000 2.429 1.965 2.106 2.380
Difference (%) 0.0 0.1 0.4 0.8 0.6
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FloEFD Validation: Smoothing step-shaped velocity profile by a porous screen of different drag coefficient ( ζ )
References2. Panton, R.L., Incompressible Flow. 2nd ed., John Wiley & Sons, Inc., 1996
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Flow Streamlines: Smoke Visualisation, left (Ref 19), FloEFD result, right
𝑅𝑗𝑎 = ൗ𝑇𝑚𝑎𝑥 − 𝑇𝑎𝑚𝑏
𝑄𝑅𝑗𝑎𝑒𝑥𝑝 = 43𝑜𝐶/𝑊 (Ref 14)
𝑅𝑗𝑎𝑐𝑎𝑙𝑐 = 41𝑜𝐶/𝑊
FloEFD Validation: Cooling a Pin-Fin Heat Sink Due to Natural Convection
References14. Enchao Yu, Yogendra Yoshi: Heat Transfer Enhancement from Enclosed Discrete Components using Pin-Fin Heat Sinks Int. J. of Heat & Mass Transfer, v. 45, pp. 4957-4966 (2002)19. Jyotsna, R., Vanka, S.P.: Multigrid Calculation of Steady, Viscous Flow in a Triangular Cavity. J. Comput. Phsy., v. 122, pp. 107-117 (1995)
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Caviatition on a Hydrofoil (1); QuantitativeComparison
Cavitation Number, 𝜎 =𝑃∞−𝑃𝑣1
2𝜌𝑈2
Pressure Coefficient vs. Cavitation NumberCavitation Length vs. Cavitation Number
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V=8 m/s, Chord length = 0.305 m
Angle of attack () – 3.5о
Cavitation number,
Caviatition on a Hydrofoil (2); QualitativeComparison
Reference
24. Wesley, H.B., Spyros, A.K.: Experimental & Computational Investigation of Sheet Cavitationon a Hydrofoil. Presented at 2nd Joint ASME/JSME Fluid Engineering Conference & ASME/EALA 6th
International Conference on Laser Anemometry. The Westin Resort, Hilton Head Island, SC, USA August 13-18, 1995
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Component Mass Fraction, %
Fuel (Methane) 3.29
Oxidizer (Air) 96.71
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Reference
27. Nandula, S.P., Pitz, R.W., Barlow, R.S., Fiechtner, G.J., Rayleigh/Raman/LIF Measurements in a Turbulent Lean Premixed Combustor” AIAA 96-0937, 34th Aerospace Sciences Meeting & Exhibit, Reno, NV, January 15-18, 1996
Combustion of a Premixed Methane/Air Mixture
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FloEFD Validation: Flow in a 90o-bend of a 3D square duct
Velocity profiles at different cross sections in different longitudinal planes
AA1
AA1
Reference8. Van Dyke, Milton, An Album of Fluid Motion. The Parabolic Press, Stanford, California, 1982.
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Hydraulic resistance coefficient Torque coefficient
Flow through a Cone Valve
Reference13. Yanshin, B.I.: Hydrodynamic Characteristics of Pipeline Valves and Elements.Convergent Sections, Divergent Sections, and Valves. “Mashinostroenie”, Moscow,1965.
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-1
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Ct, experimet
Ct, EFD.Lab
Cn, experiment
Cn, EFD.Lab
-0,04
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mz
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Experiment
Calculation
Aerodynamic drag coefficient vs. attack angleAerodynamic torque coefficient vs. attack angle
Supersonic air flow at incident M=1.3 over a segmental conic body at different attack angles in the 0…180° range.
Supersonic Flow over a Segmental Conic Body
Reference5. Artonkin, V.G., Petrov, K.P., Investigations of aerodynamic characteristics ofsegmental conic bodies. TsAGI Proceedings, No. 1361, Moscow, 1971 (in Russian).
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Flow Around the Ahmed Car Body
Slant angle = 35°
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Reference
Lienhart, H., Stoots, C., Becker, S. Flow and turbulence structures in the wake of a
simplified car model (Ahmed model). DGLR Fach Symp. der AG STAB, Stuttgart University,
2000.
AhmedBody Slant Angle
𝑪𝒅𝒆𝒙𝒑 𝑪𝒅𝑭𝒍𝒐𝑬𝑭𝑫Absolute
Difference%
Difference
25° 0.298 0.284 -0.014 -4.8
35° 0.257 0.274 0.017 6.6
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Injection of a particle into a uniform fluid flow field:
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analytical solution
Re = 0.1
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Vp = 1 m/s,analytical solution
Vp = 1 m/s,EFD.Lab
Vp = 2 m/s,analytical solution
Vp = 2 m/s,EFD.Lab
Vp = 3 m/s,analytical solution
Vp = 3 m/s,EFD.Lab
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EFD.Lab
Re = 105
Particle trajectory in the Y-direction gravity
Dispersed-phase flows (droplets and solid particles’ trajectories)
Reference18. Henderson, C.B. Drag Coefficients of Spheres in Continuum and Rarefied Flows.AIAA Journal, v.14, No.6, 1976.
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Comparison of predicted and measured total pressure
drop for a Stairmand HE cyclone
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EFD calculations
Time evolution of the total pressure drop of a Stairmand HE
cyclone at 10 m/s gas inlet velocity
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Stairmand High Efficiency Gas Cyclone (Non-isotropic swirling Flows)
Reference Griffiths, W.D., Boysan, F., 1996, “Computational fluid dynamics (CFD) and empirical modellingof the performance of a number of cyclone samplers”, J. Aerosol Sci, Vol 27, №2, 281-304
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Reference
Winklhofer, E., Kull, E., Kelz, E., and Morozov, A., 2001, “Comprehensive Hydraulic and Flow Field Documentation in Model Throttle Experiments Under Cavitation Conditions.”
ILASS Europe 2001.
L=0.001 m, H=0.000299 m,
W=0.0003 m, Rin=0.00002 m
100 bar
33 bar
100 bar
100 bar
25 bar
15 bar
Mass flow rate through the injector versus pressure drop
0.004
0.005
0.006
0.007
0.008
0.009
20 30 40 50 60 70 80 90 100
(Pin - Pb), bar
G, k
g/s
calculation
experiment
Fuel Injector Cavitation
Inlet
Outlet
Nozzle Wall
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Modified equilibrium combustion model approach in FloEFD:— Combustion starts upon mixing (no pre-mixing)— “Limited Combustion Rate” option when
premixed. Requires the separate simulation of an igniter to start the combustion simulation
FloEFD Validation: Vortex Combustor Benchmark
BERL Combustor
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Position [m]
Tem
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atu
re o
f F
luid
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]
X=0.027
ReferenceSayre A, N. Lallemant, J. Dugue, R. Weber, 1994, Scaling Characteristics of Aerodynamics and Low-NOx Properties of Industrial Natural Gas Burners, The Scaling 400 Study, Part IV: The 300 kW BERL Test Results, IFRF Doc No F40/y/11, The Netherlands.