Experimental Thr ee-Dimensional V elocity Data of
a Sweeping Je t from a Fluidic Oscillat or
Interacting with a Crossflo w
F . Os termann , R. W oszidlo, C.N. N a yeri, and C.O. P aschereit
Hermann-Föttin ger -Institut
Technisc he Universit ä t Berlin
September 28, 2018
Introduction
Jets in crossflo w are a fundamental flo w scenario f or a variety of technical applications (e.g., c himne y s,
fuel injection, and flo w control). Especiall y in flo w control, spatiall y oscillating jets (i.e., sw eeping
jets) emitted from fluidic oscillators into a crossflo w ha v e pro v en to be effectiv e in, f or e x ample,
mixing enhancement
1
, separation control
2
, drag reduction
3
, and film cooling
4
. Fluidic oscillators are
de vices that are able to g enerate spatially and/or temporall y oscillating jets without the need of mo ving
par ts because the oscillation is solel y caused b y the internal flo w dynamics. Ho w e v er , the dr iving
mechanisms behind the effectiv eness of fluidic oscillators in flo w control ha v e remained unclear
because the fundamental flo w field dynamic is unkno wn. The main reasons f or this shor tcoming are
the requirements f or a high spatial and concur rentl y high temporal resolution f or understanding the
comple x interactions within the three-dimensional flo w field.
As f ar as the authors are a w are, the included dataset is the first e xper imentall y acq uired data that
captures the quasi-time-resol v ed, three-dimensional flo w field of a spatiall y oscillating jet interacting
with an attached crossflo w o v er a flat plate. It ser v ed as the basis f or se v eral publications
5–7
, one
video a w arded with the Milton-van-Dyk e a w ard
8
, and one PhD thesis
9
. F ur ther more, the data has
been consulted f or v alidation of CFD s tudies 10,11 .
The dataset is published in order to offer a basis f or future studies on spatiall y oscillating jets in
crossflo w f or other researc hers and enable a simple access to the data f or v alidation of CFD s tudies.
Further more, it is a suitable dataset f or tes ting ne w data analy sis and visualization approaches.
1

Experimental Setup
Most e xper imental details are descr ibed in the associated publications. Here, onl y the main f acts are
summar ized and additional details are pro vided that ma y be of par ticular interest when w orking with
the pro vided data.
The e xper iments w ere conducted in an open retur n wind tunnel at the Her mann-Fötting er -Institut
of the T ec hnisc he U niv ersität Ber lin in the y ears 2016–2018. A schematic of the wind tunnel is
illustrated in figure 1. The wind tunnel is able to pro vide v elocities up to
25 m/s
at a turbulence le v el
of 0.15%. The wind tunnel v elocity is measured using a Pitot-s tatic tube. The measurement section
is
2.5 m
long and has a cross-section of 55
× 55 cm 2
. An adjustable ceiling allo w s to modify the
stream wise pressure gradient (figure 1, 7). For the presented dataset, this gradient is set to zero. A
splitter plate is installed inside the measurement section to build up a fresh boundary la y er (figure 1,
6). The splitter plate reduces the height of the measurement section to appro ximatel y
35 cm
. The
boundar y la y er is a full y turbulent flat plate boundary lay er . A t the position of the jet injection,
its 99%-thic kness is
16 mm
on a v erag e and its momentum thic kness is
1.6 mm
. Depending on the
crossflo w v elocity , the 99%-thickness v ar ies betw een 13 and
19 mm
. The boundar y la y er v elocity
profiles w ere measured using a Pitot tube with a diameter of
0.3 mm
. The boundar y la y er profiles
f or three crossflo w v elocities are pro vided in the f older
boundaryLayer
. The individual UTF-8
encoded csv -files include the measurement settings, ambient conditions, and the stream wise v elocities
at v arious distances from the splitter plate.
inflo w
1 2
3 4 5
6
7
8 9
10
11
12
h
1 hone y comb h
2 mesh screen h
3 inlet nozzle h
4 test section
h
5 fluidic oscillator h
6 splitter plate h
7 adjustable ceiling h
8 trailing edg e flap
h
9 hone y comb h
10 rotor & stator h
11 engine h
12 tra v ersing sy stem
1.8 m 2.5 m 2.1 m

Figure 1: Sc hematic of the emplo y ed wind tunnel. 9
The spatiall y oscillating jet is created b y a fluidic oscillator with tw o f eedback c hannels. The
emplo y ed g eometr y of the oscillator is pro vided along with the presented dataset as a s tep file
(
fluidic_oscillator.STEP
). The g eometry is based on a patent b y S touffer and Bo w er
12
. The
flo w dynamics inside the oscillator are in v estig ated b y Oster mann et al.
13
and Sieber et al.
14
. The
2

outlet nozzle throat of the oscillator is 10
× 10 mm 2
. The oscillator is installed inside the splitter plate.
Its installation angles are chosen so that the vir tual plane spanned b y the sw eeping jet is per pendicular
to the direction of the crossflo w (i.e., 90 deg injection angle and no sk e w angle). The suppl y rate of
the oscillator is pro vided b y a massflo w controller . The v elocity ratio
R
is defined as the ratio betw een
the theoretical bulk jet v elocity
U b u l k
and the crossflo w v elocity
U ∞
(Eq. 1). The bulk v elocity is
deter mined from the supplied massflo w
Û
m s u p p l y
assuming ambient conditions (i.e., the ambient
density ρ 0 ) and a top-hat v elocity profile at the nozzle throat with the outlet area A ou t l et ( E q . 2 ) .
R = U b u l k
U ∞
(1)
U b u l k =
Û
m s u p p l y
ρ 0 A ou t l et
(2)
It is impor tant to note that the iner tia of the fluid suppl y chain does not allo w f or compensating
temporal oscillations in the suppl y rate. Hence, the pro vided massflo w is the time-a v erag ed massflo w .
Ear lier s tudies re v ealed that the massflo w e xiting the nozzle oscillates temporall y due to an oscillating
counter -pressure.
13
Although these oscillations are small (of the order of 10%), this ma y cause
discrepancies betw een the dataset and numerical simulations that assume a constant suppl y rate as a
boundar y condition at the inlet.
The v elocity data is acquired b y emplo ying a s tereoscopic par ticle imag e v elocimetr y (PIV) sys tem.
The PIV sy s tem is able to capture the three-dimensional v elocities inside a tw o-dimensional plane
at a sampling rate of
6 Hz
. A tra v ersing sy s tem enables to mo v e the complete PIV sy s tem in the
stream wise and the span wise direction. This allo w s f or acquiring the three-dimensional v elocity
field plane-b y -plane. The acquired data e xtends appro ximatel y 165 mm in the crossflo w s tream wise
direction,
140 mm
in the direction nor mal to the w all, and up to
120 mm
in the span wise direction.
The e xtent of the v olume is doubled when consider ing the symmetr y of the flo w field, which is
e xplained later . The individuall y measured planes are or iented in the stream wise and the w all-normal
direction. The span wise direction is sampled b y up to 22 planes. F or eac h plane, up to
8000
flo w
field snapshots are recorded. Theref ore, the acq uisition of eac h three-dimensional flo w field results in
more than fiv e terab ytes of data. A dded to that are around 25 da y s of computing time required f or
e xtracting the instantaneous v elocity fields. Accordingl y , the complete included dataset (i.e., f our
three-dimensional flo w fields) is e xtracted from 20 terab ytes of ra w data, which took appro ximatel y
100 da y s of computing time. The snapshots w ere ev aluated using PIVVie w3C b y PIVT ec.
The v elocity fields are phase-a v erag ed in order to eliminate stoc has tic noise, compensate f or the
small PIV sampling rate, and pro vide a temporal cor relation betw een the individuall y measured planes.
The data is phase-a v erag ed based on a ref erence signal as sugg es ted and v alidated b y Ostermann
et al.
15
f or an oscillating flo w field of a fluidic oscillator . The ref erence signal is e xtracted from
simultaneousl y conducted pressure measurements inside the oscillator . The ref erence signal is used
f or identifying the individual oscillation per iods. This inf or mation is used to assign one phase-angle
3

to each PIV snapshot. All snapshots within a phase-angle windo w are av eraged. The oscillation
per iod is divided into 120 phase-angle windo ws with a windo w size of 3 deg. The star ting point of the
oscillation per iod is chosen someho w arbitrar il y but consistentl y betw een the individual measurements.
It is set to zero pressure difference betw een the f eedbac k c hannel inlets, which appro ximately coincides
with the jet lea ving the nozzle at zero deflection. This phase-av eraged pressure difference is pro vided
in the
pressureData.csv
of each measured scenario. The positions of the pressure sensors are
mark ed b y small cy linders located at the oscillator w all in fluidic_oscillator.STEP .
It is note w or th y that onl y half of the symmetr ic flo w field is captured and included in the dataset
(i.e.,
z >
0 ). The other half of the flo w field is obtainable b y accounting f or the symmetr y and the
phase-lag betw een both sides ∆ φ = 180 ◦ (Eq. 3).
©


«
u ( x , y , − z , φ )
v ( x , y , − z , φ )
w ( x , y , − z , φ )
ª
®
®
¬
=
©


«
u ( x , y , z , φ + 180 ◦ )
v ( x , y , z , φ + 180 ◦ )
− w ( x , y , z , φ + 180 ◦ )
ª
®
®
¬
(3)
The measured data o v er laps the plane of symmetry (i.e., the
x
-
y
-plane at
z =
0 ) b y up to
8 mm
, which
allo ws f or a smooth transition betw een the measured and mirrored data. This smooth transition ma y
be achie v ed b y a w eighted a v erag e of the symmetr ic and or iginal data with a linear transition from
onl y symmetric flo w field at
z mi n
of the o v er lap o v er the same w eight at
z =
0 to onl y original data at
z m a x of the o v er lap.
Data Format
The dataset includes the three-dimensional, quasi-time-resol v ed v elocity fields of f our scenar ios. The
k e y parameters of the scenar ios are summar ized in table 1. The flo w fields of three different v elocity
ratios (i.e., R1, R3, and R5) and one different oscillation frequency at a giv en v elocity ratio (i.e., T2)
w ere measured.
name v elocity ratio oscillation frequency U b u l k U ∞
R1 1.0 23.4 Hz 15.0 m/s 15.0 m/s
T2 3.0 34.1 Hz 22.5 m/s 7.50 m/s
R3 3.0 66.8 Hz 45.0 m/s 15.0 m/s
R5 5.0 72.1 Hz 50.0 m/s 10.0 m/s
T able 1: Included Scenar ios
The ambient conditions dur ing the measurements are pro vided in the respectiv e file
conditions.txt
that is located in the f older of each scenario. The file
pressureData.csv
contains the pressure
difference betw een tw o positions inside the oscillator that are marked as small cy linders in the file
fluidic_oscillator.STEP
. This pressure data is pro vided f or the phase-alignment of other data
to the presented dataset.
4

The te xt file
gridDefinition.txt
pro vides the dimensions and size of the str uctured gr id of
each scenario. The emplo y ed coordinate sy stem origin is located in the middle of the oscillator outlet
with
z =
0 being located at the w all (i.e., the splitter plate). The coordinate
x
is or iented in the
crossflo w direction and the coordinate
y
is or iented nor mal to the w all. It is note w or th y that the g r id
is not the same betw een the scenarios. Further more, it is not unif or mly spaced in the z -direction.
Each scenario contains a f older
data
that contains the data files. F or eac h phase-angle, one
cor responding data file is pro vided. In total, 120 phase-angles are pro vided f or each scenar io. The
name of the files represent the phase-angles in degree. The files are comma-separated UTF-8 data
files. Each line, beginning from the second line, contains one v elocity v ector with its components
u
,
v
, and
w
in
m/s
at a point
x
,
y
, and
z
in
mm
. The points are sorted by their coordinate. All points
tog ether f or m the af orementioned str uctured gr id.
It is impor tant to note that the pro vided precision of the numbers does neither represent the
actual precision of the measured v elocities nor account f or the uncertainty of the PIV measurements.
Although the data is pro vided at a precision of 1/100th of
1 m/s
, the PIV measurement uncer tainty is
e xpected to be considerably higher . Ho w e v er , the uncertainty has not been quantified because, so f ar ,
no reliable nor con v enient procedure of quantifying the uncer tainty of stereoscopic PIV measurements
e xist.
In v estig ating the three-dimensional, quasi-time-resol v ed flo w field requires pos t-processing tools
that are able to handle the amount of data. One quic k possibility f or a first e xploration using
P araV ie w 5.5.0 16 is descr ibed in the f ollo wing:
1. Extract the dataset b y using an y appropr iate e xtraction tool (e.g., 7zip, gzip).
2. Open one of the csv -files with para vie w . It should no w parse the file inside a table.
3.
Select the table in the Pipeline Br o w ser and clic k F ilter s
→
Alphabetical
→
T able T o S tructur ed
Grid . Ignore the er ror messag es that ma y pop up.
4.
Inside the Pr operties -windo w choose
x(mm)
as X Column ,
y(mm)
as Y Column , and
z(mm)
as Z
Column . Fur ther more, enter the gr id-size pro vided in the cor responding
gridDefinition.txt
to the Whole Extent -te xt fields. For e xample, f or
x_size=186
,
y_size=126
, and
z_size=25
,
as noted in the gridDefinition.txt enter:
Whole Extent 0 185
0 125
0 24
5.
Clic k on Apply if necessar y and chang e the visibility of the ne w added object to visible in the
Pipeline-Br o w ser . N o w it is sa v e to clear all er rors because no ne w one should pop up.
5

6.
In order to merg e the three scalars
u
,
v
, and
w
to a v ector , add a calculator filter ( F ilter s
→
Common → Calculator ). In the f or mula te xt field enter:
u(m/s)*iHat + v(m/s)*jHat + w(m/s)*kHat
7.
One phase-angle of the data is no w successfully added. Consult the P araV ie w documentation
or the multitude of a v ailable tutor ials f or further steps to e xplore the data.
R ecall that onl y one half of the flo w field is included in the pro vided data. The other half needs to be
reproduced with Eq. 3 using an y pos t-processing tool. Generall y , it is recommended to read the data
with a post-processing tool of y our choice and sa v e the data ag ain in an appropriate binar y f or mat
because this most lik ely reduces the loading times significantl y .
Another possibility f or a more quantitativ e in v estig ation of the flo w field is f or e xample pro vided
b y Matlab 17 . The f ollo wing code snippets impor ts data from one times tep using Matlab 2017b:
% import csv file
data = csvread(fullfile(path_to_files,’000.csv’),1,0);
% reshape to grid using the information from the gridDefinition.txt
% for example x_size=186, y_size=126, and z_size=25
x = reshape(data(:,1),[186,126,25]);
y = reshape(data(:,2),[186,126,25]);
z = reshape(data(:,3),[186,126,25]);
u = reshape(data(:,4),[186,126,25]);
v = reshape(data(:,5),[186,126,25]);
w = reshape(data(:,6),[186,126,25]);
Of course, the same procedure is also transf erable to other prog ramming languag es. N ote that
this code reads the data in
ndgrid
-f or mat. For
meshgrid
-f or mat an additional rear rangement of
dimensions is necessar y . This code snippet onl y impor ts one half of the flo w field that is captured in
the data. The other half ma y be obtained f ollo wing Eq. 3.
6

Associated Publications
The pro vided data is par t of the discussions in f ollo wing publications:
F . Ostermann, R. W oszidlo, C. N. N a y er i, and C. O. Pasc hereit. The time-resol v ed flo w field of a jet
emitted b y a fluidic oscillator into a crossflo w . In 54th AIAA A er ospace Sciences Meeting . Amer ican
Institute of A eronautics and Astronautics, Jan 2016. doi:10.2514/6.2016-0345.
F . Ostermann, R. W oszidlo, C. N. N a y er i, and C. O. Pasc hereit. Effect of v elocity ratio on the flo w
field of a spatiall y oscillating jet in crossflo w . In 55th AIAA A er ospace Sciences Mee ting . American
Institute of A eronautics and Astronautics, Jan 2017. doi:10.2514/6.2017-0769.
F . Ostermann, P . Godbersen, R. W oszidlo, C. N . N a y eri, and C. O. Pasc hereit. Sw eeping jet from a flu-
idic oscillator in crossflo w . Physical R eview Fluids , 2(9), Sep 2017. doi:10.1103/ph y sre vfluids.2.090512.
F . Ostermann, R. W oszidlo, C. N. N a y er i, and C. O. Pasc hereit. The interaction betw een a spatially
oscillating jet emitted b y a fluidic oscillator and a crossflo w . Jour nal of Fluid Mec hanics (under
r evision) , 2018.
F . Ostermann. F undamental proper ties of a spatiall y oscillating jet emitted b y a fluidic oscillator .
Doctor al Thesis at the T ec hnisc he U niv er sität Ber lin , 2018. doi:10.14279/depositonce-7144.
A cknowledgements
This w ork was funded b y the Deutsche F orsc hungsg emeinschaft (DFG Project 289230680), whic h
the authors gratefully ac kno w ledg e. F ur ther more, the authors are thankful f or the team of the
Her mann-Fötting er -Institut and the s tudents (par ticularl y Marc Feldwisc h, Sasc ha Mar tink e, Philipp
Godbersen, and Edg ar R och) that contr ibuted a significant amount of w ork to the setup of the
e xper iments and data acquisition.
References
[1]
A. Lacarelle and C. O. P asc hereit. Increasing the passiv e scalar mixing quality of jets in
crossflo w with fluidics actuators. Jour nal of Engineering f or Gas T urbines and P ow er , 134(2):
021503, 2012. doi:10.1115/1.4004373.
[2]
R. Seele, P . T e w es, R. W oszidlo, M. A. McV eigh, N. J. Lucas, and I. J. W y gnanski. Discrete
Sw eeping Jets as Tools f or Impro ving the Perf or mance of the V-22. AIAA Journal of Aircr af t ,
46(6):2098–2106, 2009. doi:10.2514/1.43663.
7

[3]
H.-J. Sc hmidt, R. W oszidlo, C. N. N a y er i, and C. O. Pasc hereit. Drag reduction on a rectangular
bluff body with base flaps and fluidic oscillators. Experiments in Fluids , 56(7), Jul 2015. ISSN
1432-1114. doi:10.1007/s00348-015-2018-3.
[4]
M. A. Hossain, R. Prenter , R. K. Lundg reen, A. Amer i, J. W . Gregor y , and J. P . Bons. Exper i-
mental and numer ical in v estig ation of sw eeping jet film cooling. Jour nal of T urbomac hiner y ,
140(3):031009, Dec 2017. doi:10.1115/1.4038690.
[5]
F . Ostermann, R. W oszidlo, C. N. N a y er i, and C. O. Pasc hereit. The time-resol v ed flo w field of
a jet emitted b y a fluidic oscillator into a crossflo w . In 54th AIAA A er ospace Sciences Mee ting .
Amer ican Institute of A eronautics and Astronautics, Jan 2016. doi:10.2514/6.2016-0345.
[6]
F . Ostermann, R. W oszidlo, C. N. N a y er i, and C. O. P asc hereit. Effect of v elocity ratio on the
flo w field of a spatially oscillating jet in crossflo w . In 55th AIAA Aer ospace Sciences Meeting .
Amer ican Institute of A eronautics and Astronautics, Jan 2017. doi:10.2514/6.2017-0769.
[7]
F . Ostermann, R. W oszidlo, C. N . N a y er i, and C. O. P asc hereit. The interaction betw een a
spatiall y oscillating jet emitted b y a fluidic oscillator and a crossflo w . Jour nal of Fluid Mec hanics
(under r evision) , 2018.
[8]
F . Ostermann, P . Godbersen, R. W oszidlo, C. N . N a y er i, and C. O. P aschereit. Sw eep-
ing jet from a fluidic oscillator in crossflo w . Phy sical R eview Fluids , 2(9), Sep 2017.
doi:10.1103/ph y sre vfluids.2.090512.
[9]
F . Ostermann. Fundamental proper ties of a spatiall y oscillating jet emitted b y a fluidic oscillator .
Doctor al Thesis at the T ec hnisc he U niv ersität Ber lin , 2018. doi:10.14279/depositonce-7144.
[10]
M. A. Hossain, R. Prenter , R. K. Lundgreen, L. A gr icola, A. Amer i, J. W . Gregor y , and J. P . Bons.
In v estig ation of crossflo w interaction of an oscillating jet. In 55th AIAA Aer ospace Sciences
Meeting . American Institute of A eronautics and Astronautics, Jan 2017. doi:10.2514/6.2017-
1690.
[11]
S. Aram, H. Shan, F . Ostermann, and R. W oszidlo. Computational validation and anal y sis of
interaction of a sw eeping jet and an attached turbulent flo w . In 2018 AIAA Aer ospace Sciences
Meeting . American Institute of A eronautics and Astronautics, Jan 2018. doi:10.2514/6.2018-
1798.
[12]
R onald D. Stouffer and R ober t Bo w er . Fluidic flo w meter with fiber optic sensor. P atent US
5827976, 1998.
[13]
F . Ostermann, R. W oszidlo, C. N a y eri, and C. O. Pasc hereit. Experimental Compar ison betw een
the Flo w Field of T w o Common Fluidic Oscillator Designs. 53rd AIAA A er ospace Sciences
Meeting , January 2015. doi:10.2514/6.2015-0781.
8

[14]
M. Sieber , F . Oster mann, R. W oszidlo, K. Ober leithner , and C. O. Pasc hereit. Lag rangian
coherent structures in the flo w field of a fluidic oscillator. Phy sical R eview Fluids , 1(5), 2016.
ISSN 2469-990X. doi:10.1103/Ph y sR e vFluids.1.050509.
[15]
F . Ostermann, R. W oszidlo, C. N. N a y er i, and C. O. Pasc hereit. Phase- A v eraging Methods f or
the N atural Flo wfield of a Fluidic Oscillator. AIAA Journal , 53(8):2359–2368, A ug 2015. ISSN
1533-385X. doi:10.2514/1.j053717.
[16] Kitw are, Inc. P ara vie w . URL https://www . paraview . org .
[17] MathW orks. Matlab. URL http://www . mathworks . com /products/matlab . html .
9

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