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Exp: CFDVAL2004 Case 2 Details and Submission Guidelines

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Relevant details for Case 2 are as follows:

M_freestream = 0.10

The atmospheric conditions varied, but were essentially standard atmospheric conditions at sea level in a wind tunnel vented to the atmosphere, in a temperature-controlled room. These conditions can be given as approximately:

p_ambient = approx 101325 kg/(m-s^2)

T_ambient = approx 75 deg F (approx 297 K)

Some derived relevant conditions are:

density_ambient = approx 1.185 kg/m^3

viscosity_ambient = approx 18.4e-6 kg/(m-s)

u_freestream = approx 34.6 m/s

Re_freestream = approx 2.23e6 per meter

The upstream boundary conditions from the experiment (associated with the boundary layer on the plate at location x=50800 microns (50.8 mm) upstream of the center of the jet orifice), to be used to help set/verify CFD inflow BCs, are given in the following file:

LV-derived Upstream BCs from experiment

The diaphragm frequency = 150.0 Hz. The "neutral position" of the moveable diaphragm plate at rest inside the cavity is approximately 2.8 mm below the upper cavity wall (see Geometry page for details). However, when the wind tunnel is on and when the moveable piston is operating, the neutral position of the plate moves up so that it is approximately 1.7 mm below the upper cavity wall. This change in the neutral position is not accounted for in the current CFD grids available from this website. However, it is not known whether accounting for this shift is important or not. The plate then displaces sinusoidally about this new neutral position with a maximum displacement of approximately +-0.77 mm. The following file lists data from the cavity, including cavity pressure, voltage input, and displacement data about its neutral position:

Driver BCs from experiment, updated 24 December 2003

The pressure is measured inside the cavity on its top wall, to one side of the orifice, approximately on the order of 10 mm from the side wall. The pressure is measured with respect to the tunnel static pressure.

The following figure (updated on 24 December 2003) shows the measured phase-averaged streamwise and vertical velocities over the (approximate) center of the orifice as a function of phase.

plot of near-centerline velocities as function of phase

These LV-derived data over the orifice (plus other quantities of interest) are given in the following file:

OverExitrevised.dat, updated 12 February 2004 (minor fix: previous file label had X, Y, and Z in microns... it should have said mm)

Note in the data file that the spanwise (v) velocity as measured is not near zero.

Submission Guidelines:

(Last updated: 24 December 2003)

Numerical predictions of this type of statistically unsteady flow are relatively new. The purpose here is to determine the state-of-the-art in modeling these types of unsteady synthetic-jet-type flows, so we want to explore which CFD methods work and which do not.

You can either model the internal cavity or specify an unsteady boundary condition at the orifice exit.
You may choose to model the moving diaphragm, or you may employ an unsteady boundary condition that approximates its effect within the cavity.

There is the requirement that you detail specifically how you choose to model the case, including all boundary conditions and approximations made. As we assess the methodologies used at the workshop, it will be important to know as many details as possible about the calculations/simulations.

Detailed requirements include:

1. The case must be run time-accurately and in three-dimensions, in order to simulate the unsteady 3-D nature of the case.

1a. RANS codes run in time-accurate mode (e.g., URANS) solve directly for phase-averaged variables, i.e. <u_i> and <u'_iu'_j>. Click on link to PDF write-up for more details. Therefore, RANS simulations should result in repeating or very-nearly-repeating periodic solutions. When periodicity is achieved, averages over one or more periods of oscillation yields the long-time-averaged (time-independent mean) values for these quantities.
1b. DNS, LES, or DES simulations will need to be post-processed to obtain both the phase-averaged and long-time-averaged (time-independent mean) values.

2. GRID STUDY: Solutions using more than one grid size are encouraged, but not required. If you use more than one grid, submit each set of results separately.

3. TIME STEP STUDY: Solutions using more than one time step are encouraged, but not required. If you use more than one time step, submit each set of results separately.

Specific quantities that result from your computations at particular locations will be required for submission. Note that for all the following, we adopt the coordinate system with x downstream, z up, and y spanwise, with the (x,y,z)=(0,0,0) origin on the tunnel splitter plate 8 diameters (50.8 mm) directly upstream of the center of the orifice (the orifice diameter is 0.25 inches = 6.35 mm). The requirements follow (if you are unable to provide a particular quantity, simply leave it out of the "variable" list, and reduce the number of columns of data submitted):

a. Long-time-averaged downstream velocity (u), spanwise velocity (v), and
vertical velocity (w) profiles (nondimensionalized by Uinf) along
vertical lines at the centerplane (y=0) and: x=0 mm, x=44.45 mm (-1D upstream),
x=50.8 mm (center of orifice),
x=57.15 mm (1D downstream), x=63.5 mm (2D downstream), x=76.2 mm (4D downstream),
and x=101.6 mm (8D downstream).  Give these data to at least a height of 50 mm.
Also, submit horizontal lines of results at
x=57.15 mm and: z=5 mm, z=10 mm, and z=20 mm; and also at
x=63.5 mm and: z=5 mm, z=10 mm, and z=20 mm.  Give these data to at least a
width of 25 mm to either side of the orifice.  Also, submit horizontal
lines of results at y=0, z=0.4 mm over the slot (from approx x=47.625 mm to
x=53.975 mm), and at y=0, z=10 mm from at least x=45 mm to x=70 mm.
   Name this file: case2.avgvel.ANYTHING.dat
    -where "ANYTHING" can be any descriptor you choose (should
     be different for each file if you are submitting multiple
     runs)
    -the file should be in 6-column format:
      1st line: #your name (pound sign needed)
      2nd line: #your affiliation (pound sign needed)
      3rd line: #your contact info (pound sign needed)
      4th line: #brief description of grid (pound sign needed)
      5th line: #number of time steps per cycle (pound sign needed)
      6th line: #brief description of code/method (pound sign needed)
      7th line: #other info about the case, such as spatial accuracy (pound sign needed)
      8th line: #other info about the case, such as turb model (pound sign needed)
      9th line: #other info about the case (pound sign needed)
     10th line: variables="x, mm","y, mm","z, mm","u/Uinf","v/Uinf","w/Uinf"
     11th line: zone t="data along x=0, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf <- this is the data along x=0, y=0
     next line: zone t="data along x=44.45mm, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf <- this is the data along x=44.45, y=0
     next line: zone t="data along x=50.8mm, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf <- this is the data along x=50.8, y=0
     next line: zone t="data along x=57.15mm, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf <- this is the data along x=57.15, y=0
     next line: zone t="data along x=63.5mm, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf <- this is the data along x=63.5, y=0
     next line: zone t="data along x=76.2mm, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf <- this is the data along x=76.2, y=0
     next line: zone t="data along x=101.6mm, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf <- this is the data along x=101.6, y=0
     next line: zone t="data along x=57.15mm, z=5mm"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf <- this is the data along x=57.15, z=5
     next line: zone t="data along x=57.15mm, z=10mm"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf <- this is the data along x=57.15, z=10
     next line: zone t="data along x=57.15mm, z=20mm"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf <- this is the data along x=57.15, z=20
     next line: zone t="data along x=63.5mm, z=5mm"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf <- this is the data along x=63.5, z=5
     next line: zone t="data along x=63.5mm, z=10mm"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf <- this is the data along x=63.5, z=10
     next line: zone t="data along x=63.5mm, z=20mm"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf <- this is the data along x=63.5, z=20
     next line: zone t="data along z=0.4mm, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf <- this is the data along z=0.4, y=0
     next line: zone t="data along z=10mm, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf <- this is the data along z=10, y=0

Download sample file case2.avgvel.SAMPLE.dat (updated 9 December 2003)

b. Phase-averaged quantities at 9 different phases during
the cycle:  0 deg, 40 deg, 80 deg, 120 deg, 160 deg,
200 deg, 240 deg, 280 deg, 320 deg.; where you should align the phases of
your computation as described below.  Submit the following phase-averaged
<> quantities:  u/Uinf, v/Uinf, w/Uinf, u'u'bar/Uinf^2, v'v'bar/Uinf^2,
w'w'bar/Uinf^2, u'v'bar/Uinf^2, u'w'bar/Uinf^2, v'w'bar/Uinf^2
(nondimensionalized),
where:
   u = phase-averaged downstream velocity component
   v = phase-averaged spanwise velocity component
   w = phase-averaged vertical velocity component
   u'u'bar = phase-averaged turbulent normal stress in downstream direction
   v'v'bar = phase-averaged turbulent normal stress in spanwise direction
   w'w'bar = phase-averaged turbulent normal stress in vertical direction
   u'v'bar = phase-averaged turbulent shear stress in x-y plane
   u'w'bar = phase-averaged turbulent shear stress in x-z plane
   v'w'bar = phase-averaged turbulent shear stress in y-z plane
The locations for these data are the same as for the long-time-averaged
quantities.
   Name these files: case2.phase000.ANYTHING.dat
                     case2.phase040.ANYTHING.dat
                     case2.phase080.ANYTHING.dat
                     case2.phase120.ANYTHING.dat
                     case2.phase160.ANYTHING.dat
                     case2.phase200.ANYTHING.dat
                     case2.phase240.ANYTHING.dat
                     case2.phase280.ANYTHING.dat
                     case2.phase320.ANYTHING.dat
    -where "ANYTHING" can be any descriptor you choose (should
     be different for each file if you are submitting multiple
     runs)
    -the file should be in 12-column format:
      1st line: #your name (pound sign needed)
      2nd line: #your affiliation (pound sign needed)
      3rd line: #your contact info (pound sign needed)
      4th line: #brief description of grid (pound sign needed)
      5th line: #number of time steps per cycle (pound sign needed)
      6th line: #brief description of code/method (pound sign needed)
      7th line: #other info about the case, such as spatial accuracy (pound sign needed)
      8th line: #other info about the case, such as turb model (pound sign needed)
      9th line: #other info about the case (pound sign needed)
     10th line: variables="x, mm","y, mm","z, mm","u/Uinf","v/Uinf","w/Uinf",
        "uu/Uinf^2","vv/Uinf^2","ww/Uinf^2","uv/Uinf^2","uw/Uinf^2",
        "vw/Uinf^2"
     11th line: zone t="data along x=0, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf
       uu/Uinf^2  vv/Uinf^2  ww/Uinf^2  uv/Uinf^2  uw/Uinf^2  vw/Uinf^2 <- this is the data along x=0, y=0
     next line: zone t="data along x=44.45mm, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf
       uu/Uinf^2  vv/Uinf^2  ww/Uinf^2  uv/Uinf^2  uw/Uinf^2  vw/Uinf^2 <- this is the data along x=44.45, y=0
     next line: zone t="data along x=50.8mm, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf
       uu/Uinf^2  vv/Uinf^2  ww/Uinf^2  uv/Uinf^2  uw/Uinf^2  vw/Uinf^2 <- this is the data along x=50.8, y=0
     next line: zone t="data along x=57.15mm, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf
       uu/Uinf^2  vv/Uinf^2  ww/Uinf^2  uv/Uinf^2  uw/Uinf^2  vw/Uinf^2 <- this is the data along x=57.15, y=0
     next line: zone t="data along x=63.5mm, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf
       uu/Uinf^2  vv/Uinf^2  ww/Uinf^2  uv/Uinf^2  uw/Uinf^2  vw/Uinf^2 <- this is the data along x=63.5, y=0
     next line: zone t="data along x=76.2mm, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf
       uu/Uinf^2  vv/Uinf^2  ww/Uinf^2  uv/Uinf^2  uw/Uinf^2  vw/Uinf^2 <- this is the data along x=76.2, y=0
     next line: zone t="data along x=101.6mm, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf
       uu/Uinf^2  vv/Uinf^2  ww/Uinf^2  uv/Uinf^2  uw/Uinf^2  vw/Uinf^2 <- this is the data along x=101.6, y=0
     next line: zone t="data along x=57.15mm, z=5mm"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf
       uu/Uinf^2  vv/Uinf^2  ww/Uinf^2  uv/Uinf^2  uw/Uinf^2  vw/Uinf^2 <- this is the data along x=57.15, z=5
     next line: zone t="data along x=57.15mm, z=10mm"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf
       uu/Uinf^2  vv/Uinf^2  ww/Uinf^2  uv/Uinf^2  uw/Uinf^2  vw/Uinf^2 <- this is the data along x=57.15, z=10
     next line: zone t="data along x=57.15mm, z=20mm"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf
       uu/Uinf^2  vv/Uinf^2  ww/Uinf^2  uv/Uinf^2  uw/Uinf^2  vw/Uinf^2 <- this is the data along x=57.15, z=20
     next line: zone t="data along x=63.5mm, z=5mm"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf
       uu/Uinf^2  vv/Uinf^2  ww/Uinf^2  uv/Uinf^2  uw/Uinf^2  vw/Uinf^2 <- this is the data along x=63.5, z=5
     next line: zone t="data along x=63.5mm, z=10mm"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf
       uu/Uinf^2  vv/Uinf^2  ww/Uinf^2  uv/Uinf^2  uw/Uinf^2  vw/Uinf^2 <- this is the data along x=63.5, z=10
     next line: zone t="data along x=63.5mm, z=20mm"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf
       uu/Uinf^2  vv/Uinf^2  ww/Uinf^2  uv/Uinf^2  uw/Uinf^2  vw/Uinf^2 <- this is the data along x=63.5, z=20
     next line: zone t="data along z=0.4mm, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf
       uu/Uinf^2  vv/Uinf^2  ww/Uinf^2  uv/Uinf^2  uw/Uinf^2  vw/Uinf^2 <- this is the data along z=0.4, y=0
     next line: zone t="data along z=10mm, y=0"
     subsequent lines:  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf
       uu/Uinf^2  vv/Uinf^2  ww/Uinf^2  uv/Uinf^2  uw/Uinf^2  vw/Uinf^2 <- this is the data along z=10, y=0

Download sample file case2.phase000.SAMPLE.dat (updated 9 December 2003)

c.  Phase-averaged time-history values of <u>, <v>, and <w>
(nondimensionalized by Uinf) as a
function of phase (deg) at three approximate point locations:
(x,y,z)=(50.63, 0, 0.40)mm, (57.15, 0, 10)mm, and
(63.5, 0, 10)mm.  Give the data at
every time step taken.  In other words, if your time step yields
100 steps per cycle, then give 100 phases between 0 deg and 360 deg.
You should align the phases of your computation as described below.
   Name this file: case2.phasehist.ANYTHING.dat
    -where "ANYTHING" can be any descriptor you choose (should
     be different for each file if you are submitting multiple
     runs)
    -the file should be in 7-column format:
      1st line: #your name (pound sign needed)
      2nd line: #your affiliation (pound sign needed)
      3rd line: #your contact info (pound sign needed)
      4th line: #brief description of grid (pound sign needed)
      5th line: #number of time steps per cycle (pound sign needed)
      6th line: #brief description of code/method (pound sign needed)
      7th line: #other info about the case, such as spatial accuracy (pound sign needed)
      8th line: #other info about the case, such as turb model (pound sign needed)
      9th line: #other info about the case (pound sign needed)
     10th line: variables="phase, deg","x, mm","y, mm","z, mm","u/Uinf","v/Uinf","w/Uinf"
     11th line: zone t="x=50.63mm, y=0mm, z=0.4mm"
     subsequent lines:  phase  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf  <- this is the data at x=50.63, y=0, z=0.4
     next line: zone t="x=57.15mm, y=0mm, z=10mm"
     subsequent lines:  phase  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf  <- this is the data at x=57.15, y=0, z=10
     next line: zone t="x=63.5mm, y=0mm, z=10mm"
     subsequent lines:  phase  x(mm)  y(mm)  z(mm)  u/Uinf  v/Uinf  w/Uinf  <- this is the data at x=63.5, y=0, z=10

Download sample file case2.phasehist.SAMPLE.dat

d.  Field line-contour-plots (in one of the following formats: ps, eps, or jpg)
of long-time-averaged streamwise velocity (u/Uinf) in the planes y=0mm (centerplane),
x=57.15mm (1D downstream), and x=76.2mm (4D downstream).  
These plots should be black-and-white line plots.
The y=0 plane plot should go from approx x=45mm to 125mm and z=0 to 36mm.
The x=const-plane plots should go from approx y=-18mm to +18mm, and z=0 to 36mm.
The x-to-z ratio of the plots should be 1.0.
Plot u/Uinf line contours of -0.5 through 1.5 in increments of
0.1.  Label the contour lines, if possible.
The purpose of submitting these plots is to get
a qualitative picture of the long-time-averaged flowfield,
indicative of the dynamic range of the orifice's influence.
Altogether, submit 3 plot files.
   Name these files: case2.uavg.y0.ANYTHING.eps
                     case2.uavg.x57.15.ANYTHING.eps
                     case2.uavg.x76.2.ANYTHING.eps
(where the "eps" in this case means encapsulated postscript - use ps,
or jpg instead if appropriate).

e.  Field line-contour-plots (in one of the following formats: ps, eps, or jpg)
of phase-averaged streamwise velocity (<u>/Uinf) in the planes y=0mm (centerplane),
x=57.15mm (1D downstream), and x=76.2mm (4D downstream) at the following phases:
40 deg, 120 deg, 200 deg, and 280 deg.; where you should align the phases of your computation
as described below.  These plots should be black-and-white line plots.
The y=0 plane plots should go from approx x=45mm to 125mm and z=0 to 36mm.
The x=const-plane plots should go from approx y=-18mm to +18mm, and z=0 to 36mm.
The x-to-z or x-to-y ratio of the plot should be 1.0.  For
all plot files, plot <u>/Uinf line contours of -1.0 through 2.0 in increments of
0.1.  Either (a) plot the lines of negative velocity as dashed lines
and the lines of positive velocity as solid lines, or (b) label the
contour lines, or (c) do both.  The purpose of submitting these plots is to get
a qualitative picture of the phase-averaged flowfield at
particular selected times of interest.  Altogether, submit 12 plots files.
   Name these files: case2.phase040.y0.ANYTHING.eps
                     case2.phase120.y0.ANYTHING.eps
                     case2.phase200.y0.ANYTHING.eps
                     case2.phase280.y0.ANYTHING.eps
                     case2.phase040.x57.15.ANYTHING.eps
                     case2.phase120.x57.15.ANYTHING.eps
                     case2.phase200.x57.15.ANYTHING.eps
                     case2.phase280.x57.15.ANYTHING.eps
                     case2.phase040.x76.2.ANYTHING.eps
                     case2.phase120.x76.2.ANYTHING.eps
                     case2.phase200.x76.2.ANYTHING.eps
                     case2.phase280.x76.2.ANYTHING.eps
(where the "eps" in this case means encapsulated postscript - use ps,
or jpg instead if appropriate).

Definition of Phase for the Computations (modified 24 December 2003)

Matching the same phases with the experiment is not necessarily straightforward. One way to do it is to try to align a quantity from experiment (such as vertical velocity near the jet exit), but this can be imprecise because the CFD and experimental data are not necessarily well-behaved sine-waves. The best criteria for determining phase may in fact be a different measure altogether.

On the other hand, in this workshop we want to be able to compare CFD results with each other, so it is important to try to achieve the same phase definitions in order that all computations are similarly aligned. We have tried to choose criteria for determining phase that approximates experiment AND is specific enough so that different CFD solutions can be meaningfully compared.

Therefore, although participants are given some latitude to determine phase as appropriate, we encourage everyone to use the following steps to define phase in a uniform fashion for Case 2:

Step 1. Output vertical phase-averaged velocity (w) at the following point in space (over the orifice) as a function of your iteration or time step number: (x,y,z)=(50.63, 0, 0.40)mm. Find wmax and wmin over the course of one phase-averaged period.
Step 2. Compute the mid-value wavg=(wmax+wmin)/2
Step 3. Define Phase=50 deg as the time when your velocity at this location approximately equals wavg (INCREASING). All other phases can be referenced from this, via the following relation:

Phase=(iter-it50)*360/nstep+50

where:

iter =iteration (or time step) number

nstep=no. of time steps per cycle

it50=iteration number when Phase=50 according to the above criteria

For example, if you are running 360 steps per cycle and you match the above criteria at time step number 5492, then

Phase=iter-5442

Thus, when iter=5442, then Phase=0; when iter=5622, then Phase=180; when iter=5802, then Phase=360. Note that Phase=360 also corresponds with Phase=0 (it repeats every 360 deg). This is illustrated in the following figure (updated on 24 December 2003):

plot showing how to determine phase

As another example, say you are running 1080 steps per cycle and you match the above criteria at time step number 10002, then

Phase=(iter-10002)/3+50

Thus, when iter=9852, then Phase=0; when iter=10392, then Phase=180; when iter=10932, then Phase=360.

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