- Lorentz Center

Dynamics of Motile Phytoplankton in Turbulence
Tomographic
Imaging
La
ser
3D Optics
Oscillating
Grids
John Crimaldi
University of Colorado
Turbulence
Tank
Microscale
Patchiness
Aggregation Processes
• Coagulation
• Inertial clustering
• Motility
• Chemotaxis/Phototaxis
• Gyrotaxis
• Free-surface flows
• Passive coalescence
Crimaldi 2012
Passive Coalescence in an Obstacle wake
LCS and FTLE
Peacock (2013)
FTLE Computation
Passive Coalescence in an Obstacle wake
Concentrations
FTLE Field
Pratt, Meiss & Crimaldi, Physics of Fluids, 2015
LCS are a Template for Scalar Coalescence
Concentrations
FTLE Field
Time
Pratt, Meiss & Crimaldi, Physics of Fluids, 2015
LCS are a Template for Scalar Coalescence
Pratt, Meiss & Crimaldi, Physics of Fluids, 2015
LCS are a Template for Scalar Coalescence
Concentrations
FTLE Field
Pratt, Meiss & Crimaldi, Physics of Fluids, 2015
Ecological Fluid Dynamics Laboratory
Two-Color Laser-Induced Fluorescence
Camera 1
Kr Laser
647 nm
Camera 2
Rotating
Mirror
Zoom Beam
Expander
Ar Laser
488 nm
Dichroic
Mirror
Soltys & Crimaldi, Experiments in Fluids, 2011
Turbulent obstacle wake (Re=2000)
Shoaei & Crimaldi, in review
Free-Surface Flows
incompressibility:
for floating particles:
Particle location
with pumps off
No Flow
Particle
location with pumps on
Turbulence
Voronoi tesselation of particles with
No
Flow
pumps
off
Voronoi tesselation of particles with
Turbulence
pumps on
Voronoi tesselation of particles with
pumps off
Voronoi tesselation of particles with
pumps on
Concentration Distributions
0
10
2
Re
pdf
pdf
10
4
10
6
10
0
1
10
10
1
10
2
100
r atio
ratio
10
1
10
10
1
Re
0
10
0
1
10
1
10
C /C 0
10
Dynamics of Motile Phytoplankton in Turbulence
Tomographic
Imaging
La
ser
3D Optics
Oscillating
Grids
Turbulence
Tank
Microscale
Patchiness
Microscale Phytoplankton Patchiness in Turbulence
Image courtesy of Stocker Lab
Durham et al. 2013
Heterosigma akashiwo
Hara and Chihara 1987
10 um
Patchiness as Function of Biology & Physics
Patchiness in
-
Space
Durham et al. 2013
Patchiness in
-
Space
for Heterosigma
for turbulence tank
Patchiness in
-
Space
1-Litre Oscillating-grid Turbulence Tank
1-Litre Oscillating-grid Turbulence Tank
1-Litre Oscillating-grid Turbulence Tank
Scales of Measurement: PIV and PLIF
(b) Turbulence from PIV
(a) Experimental Apparatus
10 cm
1 cm
Image Area
Grid
Drivetrain
Grid
Drivetrain
(c) Phytoplankton from PLIF
1 mm
PIV in Oscillating Grid Tank
PIV in Oscillating Grid Tank
1 cm
ocity fluctuations in
en Lavoie corrections
e of the velocity
on
ocity vector field
r transform of the
exact:
In spite of the aforementioned advantages,
meanDirect
isotropic
turbulence chambers, there has
2.4.1
method
Dissipation
consensus in the literature as to the best method to
Invoking
the assumptions
homogeneity
and defined
isotropy,
the turbulent
energy of
dissipation
rate,
general
definition
2000, Eq.
5.128)of the turbulent energy dissipation r
defined in Eq. 1 can#be simplified to (Hinze
$ 1975)
!* " + oui oui oui ouj
"
e ¼ 2m s!
þ
;
ij sou
ij ¼2 m
1
e ¼ 15m
; oxj oxj oxj oxi
ox1
where sij is the fluctuating rate-of-strain tensor,
or
in two dimensions,
fluctuating
velocity in the xi direction and m is the
" *! " + *! " + #
$
2
2
viscosity. In
the
paper,
the
ou1Eq. 1 and throughout
ou2
ou1 ou
2
e ¼ 4m
þ
þ
summation oxconvention
applies.
Hwang
Eat
ox2
ox1 oxand
1
2
2006) *
used
particle image ve
! the large-eddy
"2 +#
80
100
3
ou2 ou2
C) size [pixels]
(PIV)
to estimate: the dissipation rate and
þ method þ
pectrum tensor
4
ox1 ox1
those results to the inertial range (IR) of an ene
uringLin
analysis
of the PIV
the
spectrum
n rate from the uncorrected
trum.
Eidelman
et method
al. (2006)
used an approximate
Hence,
the direct
for dissipation
rate calculat
ipation
rate
s (Eqs. 4, 8) proposed by
length scale
approach
to estimate
dissipatio
requires
calculations
of velocity
spatialthe
derivatives
fr
n (2007) respectively. Flow
2D approximation for
homogeneous
isotropic
turbulence
2009)fac
the
PIV
vector
maps.
We
approximate
theJong
derivatives
b
their
box.
Webster
et al.
(2004), (de
whose
flow
volume
ector
tors
approx: field is
h velocity
Effect of Grid Frequency on Turbulence
1
Intensity
Microscale
Dissipation
6
0.1
ε (mm2/s3)
RMS Intensity (mm/s), η (mm)
8
4
0.01
2
0
1
2
Grid Frequency (Hz)
3
4
0.001
PLIF with Heterosigma
Li et al., 2003
PLIF in Oscillating Grid Tank
Evidence of Flow-induced Patchiness
1.4
5
1.2
4
1
0.8
3
0.6
2
0.4
1
0.2
0
0
0.5
1
1.5
2
0
0
0.5
1
1.5
experimental
numerical
2
Patchiness in
-
Space
Niche Partitioning for different species
Niche Partitioning for different species
Gyrtactic swimmers and FTLE fields
Discussion Points
•
What is the ecological relevance of this patchiness?
•
•
patches changing constantly in time, and may or
may not be coincident with other relevant patches
(nutrients, predators, etc).
Are these types of experiments important?
• identification of better candidate species
• thoughts on ways to package a competitive
proposal