Flow description:

As shown in Fig. 1, the flow consists of two coaxial jets with opposite rotation.  The diameter of the inner jet is r₀=120 mm and the outer jet is located between r₀  and R=200 mm.  The flow is confined in a duct of the same diameter R as the outer jet.
As described in Fig. 2, the mean velocity U in x-direction has a peak at the centre, but the wake in r₀ is surrounded by a region of constant U₀ velocity (U₀=26.5 m s^-1).  In this region (approximately located between r₁=70 mm and r₂=170 mm), an azimuthal mixing layer develops, with =10 ms^-1.

The region of interest is thus located between r₁=70 mm and r₂=170 mm, where an interaction between the wake of the inner nozzle and the azimuthal mixing layer takes place, as shown in Fig. 3.

Fig. 3 also describes the local axis system (x,y,z) used in the database, in which y=0 corresponds to r=r₀ .

In this flow, a transition between a wake and a mixing layer occurs as the flow develops is x-direction.  In particular, the Reynolds stress tensor experiences a drastic change in its structure, from a dominant <u²>-component with two maxima to a dominant <w²>-component with a single maximum.  This behaviour is linked to the fact that the initial streamwise wake (U-velocity) is suddenly subjected to a transverse shear (W-velocity), which mainly produces turbulence on the <w²>-component.  Note that contrary to usual mixing layers, the direction in which the flow develops (x-direction) is normal to the mean velocity direction that creates the shear (W-velocity).  The flow thus tends to a spatially developing mixing layer very similar to a temporal mixing layer.
 

Calculation domain and definition of the flow:

This case is axisymmetric, but all the components are to be calculated (U, V, W, and, for Reynolds stress models, <u²>, <v²>, <w²>, <uv>, <uw>, <vw>).

The inlet is not located at x=0, but at x₀/r₀=10/120=0.08333.
The inlet profiles for the mean velocities and the Reynolds stresses are provided in the database (files *.0010).
 

The last experimental profiles are given at x/r₀=1000/120=8.333, so the outlet must be placed well after that location (at least L/r₀=10 is recommended).

The experiments are performed in air (kinematic viscosity=15x10^-6).  The Reynolds number based on U₀  and r₀ is Re=212,000.
 

Database:

(All the quantities are made dimensionless using r₀ =120 mm and U₀=26.5 m s^-1)

- Profiles:
The database contains profiles of the mean velocities and the Reynolds stresses at 15 locations, ranging from x=50 mm to x=1000 mm.
The files consist of two columns, for y and the variable under consideration.  They are named VAR.X, where VAR=U, W, uu, vv, ww, uv, uw or vw and X=0050, 0100, 0150, 0200, 0250, 0300, 0350, 0400, 0450, 0500, 0600, 0700, 0800, 0900 or 1000 (these numbers correspond to the location on the x-axis is mm).

Download the Mean Velocities (16k)
Download the Reynolds Stresses (33k)

- Inlet:
The files VAR.0010 are to be used as inlet boundary conditions.
V is very weak everywhere in the domain (V/U₀<1%), so V=0 is to be imposed at the inlet.
The profile of the dissipation (file Eps.0010) has been evaluated from the turbulent kinetic energy profile using a constant mixing length.  This evaluation is very close (but smoother) to the one using the eddy-viscosity assumption with =0.09.

Download the Inlet profiles (4.0k)

- Budgets:
Some terms of the budgets of the Reynolds stresses are available.  The files consist of 4 columns for Y, convection, production and turbulent diffusion, respectively.  They are named budget.VAR.X, where VAR=k, uu, vv, ww, uv, uw, vw and X=0050, 0100, 0150, 0200, 0250, 0300, 0350, 0400, 0450, 0500, 0600, 0700, 0800 or 0900.

Download the Budgets (86k)
 
 

References:

Béharelle S., Delville J. and Bonnet J.-P.(516k), On the three dimensional evolution of a wake subjected to cross shear, Turbulence and Shear Flow 11, 8-11 sept 1997, Grenoble, France.

Béharelle S., Nayeri C., Delville J., Bonnet J.-P., Fiedler H.E., Influence of the transverse shear on the development of wake flows, Advances in Turbulence VI, S. Gravilakis et al. editors, 511-512.
 
 

Required results:

Participants are invited to submit results in the same form as the database, i.e.:

(Recall that all the quantities must be scaled by r₀ =120 mm and U₀=26.5 m s^-1.)

- profiles in two-column files named VAR.X, where VAR=U, W, uu, vv, ww, uv, uw or vw and X=0050, 0100, 0150, 0200, 0250, 0300, 0350, 0400, 0450, 0500, 0600, 0700, 0800, 0900 or 1000.

- budgets of <uu>, <vv>, <ww>, <uv>, <uw>, <vw>  and k.  Irrelevant files are to be omitted (e.g., for a k-epsilon model, only k budgets are required).  The files are to be named budget.VAR.X, where VAR stands for uu, vv, ww, uv, uw, vw, k and X stands again for the location.

Each file starts with 8 comment lines beginning by a "#", consisting of:

#Case
#Name
#Affiliation
#Code/Numerical method
#Mesh type
#Turbulence model
#Any other useful information
#Column headings for the data

Examples:

File "U.0050":

#Case10.1
#Rémi Manceau
#Laboratoire d'études aérodynamiques, université de Poitiers
#Finite volumes
#Block structured
#Reynolds stress model (Speziale, Sarkar, Gatski, 1991)
#Without non-linear slow term, fine mesh
# y/r0     U/U0
 

File "budget.uu.0100"

#Case10.1
#Rémi Manceau
#Laboratoire d'études aérodynamiques, université de Poitiers
#Finite volumes
#Block structured
#Reynolds stress model (Speziale, Sarkar, Gatski, 1991)
#Without non-linear slow term, fine mesh
# Y/r0    convec   produc   t-diff    p-strain   p-diff    v-diff    dissip
 
 

File "budget.k.0900"

#Case10.1
#Rémi Manceau
#Laboratoire d'études aérodynamiques, université de Poitiers
#Finite volumes
#Block structured
#Reynolds stress model (Speziale, Sarkar, Gatski, 1991)
#Without non-linear slow term, fine mesh
#Y/r0    convec   produc   t-diff    p-strain    p-diff    v-diff    dissip
 

(N.B.: p-strain is of course supposed to be zero in the files budget.k.X.)
 

Moreover, participants are invited to submit a short description of their computations (mesh, numerical method, turbulence modelling, etc.)
Each participant will have 5 minutes to present these details (no results presentation).
 

To know how to submit the results, click here.
 
 

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