- Lorentz Center
Transcription
- 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