Welcome to my homepage - Ongoing works

1) Study of aggregation dynamics in ferrofluids in external magnetic fields

Bright-field imaging of the flow of ferrofluid in the presence of a non-uniform magnetic field produced by an electromagnet in a Confocal microscope system.
Visualization of the upstream and downstream flow field with respect to the magnet location (observance of vorticity formation and secondary flows).
Rate of aggregation of Iron-oxide nano-particles (IONPs) suspended in water (aqueous ferrofluid).
The effect of field strength, volume fraction, and flow rate is studied on the flow behavior/aggregation process.
Applications in Magnetic drug targeting, Magneto-microfluidics

Square capillary of side 1 mm; Ferrofluid: 5% v/v, particle size ~200 nm); Flow rate: 50 ul/min

50ul_min_3A_1.wmv

Video #1: Aggregation of magnetic nano- particles in ferrofluid evolving into a hump-shaped formation in an applied magnetic field

50ul_min_3A_2.wmv

Video #2: Formation of secondary flows upstream to the magnet caused by hump-shaped particle aggregates and negative magnetophoresis

50ul_min_3A_3.wmv

Video #3: Formation of secondary flows in downstream to the magnet

2) Control/manipulation of Taylor Bubble/Slug Flow of ferrofluids in confined mini/micro-channels.

Shah R. K. and Khandekar S., Manipulation of Taylor-Bubble Flow in a Magneto-Fluidic System, Colloids and Surfaces A: Physicochemical and Engineering Aspects, Feb 2020, DOI: 10.1016/j.colsurfa.2020.124589.

Air at 6 ml_min FF from 1.5 to 6 mlmin_no magnet.MOV

Video #1: No magnet case

Flow rates: Air = 6 ml/min, Ferrofluid = 1.5 to 6 ml/min

Air at 6 ml_min FF from 1.5 to 6 mlmin_magnet at Upstream position 1.MOV

Video #2: Magnet placed in downstream

Flow rates: Air = 6 ml/min, Ferrofluid = 1.5 to 6 ml/min

Air at 6 ml_min FF from 1.5 to 6 mlmin_magnet at downstream position 2.MOV

Video #3: Magnet placed in downstream

Flow rates: Air = 6 ml/min, Ferrofluid = 1.5 to 6 ml/min

3) Magnetic manipulations of Taylor flow of ferrofluid in microchannels: A phase-field based numerical investigation

Shah R. K., Drave J. K., and Khandekar S., Magnetic manipulations of Taylor flow of ferrofluid in microchannels, Proc. 7th International Conference on Micro and Nano Flows (MNF 2021), Abstract #36, Imperial College London.

022_Wednesday_Stream C (Sessions 1C).mp4

(MNF - 2021 conference presentation, Starts at: 1.45 hours)

Video 5-5: Pressure profile - No-magnet case

Video #1: Evolution of the interface, formation of bubbles and pressure profile in Taylor bubble flow of air and ferrofluid - No magnetic field case (m = 0)

Video 5-6: Pressure profile - Magnet in downstream

Video #2: Magnetic field in downstream case (m = 0.2)

Video 5-7: Pressure profile - Magnetic field in upstream

Video #3: Magnetic field in upstream case (m = 0.2)

Temperature profile - No magnet case (m = 0)

Video #1: Evolution of the interface, formation of bubbles and temperature profile in Taylor bubble flow of air and ferrofluid - No magnetic field case (m = 0)

Temperature profile - Magnet case (m = 0.4)

Video #2: Magnetic field case #1 (m = 0.4)

Video 5-9: Temperature profile - Magnet case (m = 0.8)

Video #3: Magnetic field case #2 (m = 0.8)

Droplet impact on a hydrophobic surface

Weber number (We) = 20, Contact angle = 120

We = 20, Contact angle = 155

5) On-demand augmentation in two-phase heat transfer using ferrofluids: Experimental investigation

Shah R. K. and Khandekar S., On-demand augmentation in heat transfer of Taylor bubble flows using ferrofluids (Applied Thermal Engineering, Jan 2022, DOI: 10.1016/j.applthermaleng.2022.118058).

Kole M., Shah R. K., Khandekar S., Heat transfer augmentation of air-ferrofluid Taylor bubble flow in presence of a magnet, Accepted for 4th International ISHMT-ASTFE Heat and Mass Transfer Conference (IHMTC-2021), Paper # IHMTC 2021-198.

Shah R. K., and Khandekar S., Effect of magnetic manipulation of Taylor flow of ferrofluids on two-phase heat transfer, Proc. Joint 20th International Heat Pipe Conference and 14th International Heat Pipe Symposium (Joint IHPC and IHPS - 2021), Paper #82, Gelendzhik, Russia,

(IHPC - 2021 conference presentation)