CFD for Microfluidics Application Examples Fluent Ralf Kröger, rkr@fluent.de Fluent Deutschland GmbH 2006 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary
Content Examples on what we have simualted in microfluidics Fluid transport mechanisms Drop forming (emulsions) Macroscopic Particle Model (MPM) Mixing mechanisms 2006 ANSYS, Inc. All rights reserved. 2 ANSYS, Inc. Proprietary
Why microfluidics? Advantages: Small sample volumes Decreased analysis times Readily automated Parallelizable Portable Low materials cost Challenges Minimize dispersion Enhance mixing Integration/Packaging 2006 ANSYS, Inc. All rights reserved. 3 ANSYS, Inc. Proprietary
Microfluidic Technology Applications: Biological/chemical agent detection Drug discovery (high-throughput screening) Point-of-care diagnostics DNA sequencing Drug delivery Lab on a chip Diagnostic equipment Micro-reactors Ink jet printing Industries: Food Pharma Cosmetics Medicine Biotechnology Fuel cells Quantitative gene expression results using a Polymerase chain reaction, Applied Biosystems 2006 ANSYS, Inc. All rights reserved. 4 ANSYS, Inc. Proprietary
Design concerns in microfluidic devices Transport of fluids and species and cells Droplet creation and breakup Mixing and Dispersion Reactions 2006 ANSYS, Inc. All rights reserved. 5 ANSYS, Inc. Proprietary
Transport mechanisms Neutral hydrodynamics (NHD) pressure centrifugal forces surface tension Electrohydrodynamics (EHD) electrophoresis electro-osmosis isotachophoresis 2006 ANSYS, Inc. All rights reserved. 6 ANSYS, Inc. Proprietary
Pressure Driven: Micro Pumps Pumps use a combination of nozzles and a membrane diaphragm or piezo-elements to operate FSI applications 2006 ANSYS, Inc. All rights reserved. 7 ANSYS, Inc. Proprietary
Surface Tension Driven Flows 2006 ANSYS, Inc. All rights reserved. 8 ANSYS, Inc. Proprietary
Surface Tension Driven Flow: Capillary Stops Wetting angle 45 Fluent Modul VOF small channel height 0.25 mm small channel height 1 mm 2006 ANSYS, Inc. All rights reserved. 9 ANSYS, Inc. Proprietary
Pressure Driven Flow: With surface tension effects Wetting angle 70 Fluent Modul VOF 2006 ANSYS, Inc. All rights reserved. 10 ANSYS, Inc. Proprietary
Pressure Driven Flow: With surface tension effects Fully Wetting Fluent Modul VOF 2006 ANSYS, Inc. All rights reserved. 11 ANSYS, Inc. Proprietary
Droplet generation Need to produce mono-dispersed droplets of defined size for various emulsification processes and for metering varying volumes of chemical samples. process variables are easy to manipulate 2006 ANSYS, Inc. All rights reserved. 12 ANSYS, Inc. Proprietary
Micro T junction: Water in oil emulsions Emulsions formed because droplets were pinched off by the flow fluid size of the droplet controlled by velocity of the water and oil wall surface must be hydrophobic If wall surface is hydrophilic stratified flow resulted 2006 ANSYS, Inc. All rights reserved. 13 ANSYS, Inc. Proprietary
Micro T junction: Water in oil emulsions Red Oil Blue Water Hydrophilic wall Hydrophobic wall 2006 ANSYS, Inc. All rights reserved. 14 ANSYS, Inc. Proprietary
Micro T junction: Water in oil emulsions Thanks to Mark Kielpinski Institut für Physikalische Hochtechnologie e.v. Jena BMBF Förderkennzeichen 16SV1998 2006 ANSYS, Inc. All rights reserved. 15 ANSYS, Inc. Proprietary
Micro T junction: Emulsions with defined Particle Size Distribution Link et al., Geometrically mediated breakup of drops in microfluidic devices, PRL, Feb 2004, proposed the use of T junctions with differently sized arms to generate a controlled poly-disperse emulsion 2006 ANSYS, Inc. All rights reserved. 16 ANSYS, Inc. Proprietary
Micro T junction: Symmetric breakup Fluent simulations Video from experiments http://focus.aps.org/story/v13/st4 2006 ANSYS, Inc. All rights reserved. 17 ANSYS, Inc. Proprietary
Micro T junction: Non-Symmetric breakup Ratio of the length of the arms: 1:5.2 Ratio of the size of droplets: 5.2:1 (Experimental) Ratio of the size of droplets: 5.4:1 (Fluent predictions) 2006 ANSYS, Inc. All rights reserved. 18 ANSYS, Inc. Proprietary
Micro T junction: Cascading Drop Production 2006 ANSYS, Inc. All rights reserved. 19 ANSYS, Inc. Proprietary
Micro T junction: Drop Channel Ratio is important 2006 ANSYS, Inc. All rights reserved. 20 ANSYS, Inc. Proprietary
Y-Junction 2006 ANSYS, Inc. All rights reserved. 21 ANSYS, Inc. Proprietary
Application: Ink Jet 2006 ANSYS, Inc. All rights reserved. 22 ANSYS, Inc. Proprietary
Macroscopic Particle Model 2006 ANSYS, Inc. All rights reserved. 23 ANSYS, Inc. Proprietary
Macroscopic Particle Model 2006 ANSYS, Inc. All rights reserved. 24 ANSYS, Inc. Proprietary
Macroscopic Particle Model Touched Cells Fluid Velocity Fluid Cells Particle Velocity Particle Particle Velocity imposed on touched cells 2006 ANSYS, Inc. All rights reserved. 25 ANSYS, Inc. Proprietary
Mixers Major problem with micro scale is lack of turbulence Mixers cannot use impellors Diffusion mixing is dominant Contact time is limited by device dimensions Mixer types Static mixers Vortex mixer T/Y-joints U-tube configuration Dynamic mixers Oscillating jet Mixing in drops 2006 ANSYS, Inc. All rights reserved. 26 ANSYS, Inc. Proprietary
Diffusion Effects Diffusion coefficient - 1e-9 Diffusion coefficient - 1e-10 (typical miscible liquids) Diffusion coefficient - 1e-11 2006 ANSYS, Inc. All rights reserved. 27 ANSYS, Inc. Proprietary
Oscillating jet mixer Continuous jets set up an oscillating flow Mixed product removed from both outlets Larger contact area between reagent streams then for co-flow system 2006 ANSYS, Inc. All rights reserved. 28 ANSYS, Inc. Proprietary
Mixing by secondary flows 2006 ANSYS, Inc. All rights reserved. 29 ANSYS, Inc. Proprietary
Injection adding and mixing by secondary flow in drops in channels Institut für Physikalische Hochtechnologie e.v. Jena BMBF Förderkennzeichen 16SV1998 2006 ANSYS, Inc. All rights reserved. 30 ANSYS, Inc. Proprietary
Simulation of Injection adding Institut für Physikalische Hochtechnologie e.v. Jena BMBF Förderkennzeichen 16SV1998 2006 ANSYS, Inc. All rights reserved. 31 ANSYS, Inc. Proprietary
Mixing Drop in channel: PIV results Institut für Physikalische Hochtechnologie e.v. Jena BMBF Förderkennzeichen 16SV1998 2006 ANSYS, Inc. All rights reserved. 32 ANSYS, Inc. Proprietary
Mixing vortices within moving long drop drop moves to the right (2D-simulation) in the drop reference frame wall moves to the left 2006 ANSYS, Inc. All rights reserved. 33 ANSYS, Inc. Proprietary
Mixing Drop in bending channel PIV results Institut für Physikalische Hochtechnologie e.v. Jena BMBF Förderkennzeichen 16SV1998 2006 ANSYS, Inc. All rights reserved. 34 ANSYS, Inc. Proprietary
Mixing in rotating compartments 2D rotation around center Only wall effects Two fluids 2006 ANSYS, Inc. All rights reserved. 35 ANSYS, Inc. Proprietary
Mixing in rotating compartments 2D rotation around center lab reference frame 2006 ANSYS, Inc. All rights reserved. 36 ANSYS, Inc. Proprietary
Mixing in rotating compartments 2D rotation around center moving reference frame 2006 ANSYS, Inc. All rights reserved. 37 ANSYS, Inc. Proprietary
Mixing in rotating compartments 2D rotation off center 2006 ANSYS, Inc. All rights reserved. 38 ANSYS, Inc. Proprietary
Mixing in rotating compartments 2D rotation off center moving reference frame 2006 ANSYS, Inc. All rights reserved. 39 ANSYS, Inc. Proprietary
Mixing in rotating compartments 2D rotation off center Wall and gravity effects Gravity Top light fluid (900 kg/m^3) Bottom heavy fluid (1000 kg/m^3) 2006 ANSYS, Inc. All rights reserved. 40 ANSYS, Inc. Proprietary
Mixing in rotating compartments 2D rotation off center Wall and gravity effects Interesting mixing plane 2006 ANSYS, Inc. All rights reserved. 41 ANSYS, Inc. Proprietary
Discussion CFD gives perfect simulation Much quicker to model multiple geometries All information obtained, not just at selective datum points Easy interpretation of results May need some validation to prove results 2006 ANSYS, Inc. All rights reserved. 42 ANSYS, Inc. Proprietary
Thank You! Thanks a lot for Your attention! Ralf Kröger, Fluent Deutschland GmbH, rkr@fluent.de Thanks to Rob Woolhouse, Fluent Europe Ltd, UK Marc Horner, Fluent Evanston, USA Srinivasa Mohan, Fluent India Mark Kielpinski, Institut für Physikalische Hochtechnologie e.v. Jena 2006 ANSYS, Inc. All rights reserved. 43 ANSYS, Inc. Proprietary