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(This page needs an update - please refer to recent Publications for more recent research results).
1.Mutiphysics modeling in a liquid metal battery electrode (Funded by IITB, DST-SERB, TCS Research)
One of my primary research interests is in modeling of multiphysics phenomena in liquid metal batteries including Electro-vortex flow (EVF), thermal convection, swirl, solutal convection, interface phenomena. EVF occurs due to the force produced by interaction of the current with its own magnetic field. The animation below shows the flow (in terms of velocity magnitude) that results due to electro-vortex flow in a liquid metal battery electrode (first simulated in Open FOAM by our group member, Saksham Jindal). In our group have been successful in simulating multiphysics phenomena, such as current-driven MHD flow, thermal and solutal convection, effect of external magnetic field interfacial dynamics.
We are primarily using OpenFOAM, but we also use softwares such as COMSOL. Recently, we have started some experiments, in collaboration with other faculty members.
2. Interfacial instabilities in Aluminum Reduction Cells (Funded by Hindalco)
(Details to be added)
3. Liquid metal flow and Heat Transfer under the Magnetic Field (Funded by BRNS)
(Details to be added).
Some other research interests
Evolution of a Gaussian eddy and a turbulent cloud (layer) under rotation
One of the first endeavour of my PhD work at Cambridge was to study a Gaussian eddy under rotation shown above. And if you look carefully you would know why I was hooked to the 'adorable' problem ! On a more serious note, I performed direct numerical simulations (DNS) of a rotating, localized layer (or a 'cloud') of turbulence which formed the first chapter of my thesis. The objective was to find out whether the columns that emerge out of turbulence (or out of Gaussian eddy) are inertial waves? These columns have been observed in experiments performed in the GK Batchelor Lab at Cambridge & by other physicists around the world. And yes, the columns do emerge in the box simulations, and if we colour them by the helicity (the dot product of velocity and its curl), we find that the columns are indeed nothing but low-frequency inertial wave packets!
Pearlescence (experiment) snapshots from the PhD thesis of Phil Staplehurst
Columns coming out of the layer of turbulence in 3D simulations
Columns coloured by helicity (red is +ve, blue is -ve) - this is one of the many interesting properties of inertial waves.
Column formation in the outer core of the Earth
Another problem that I worked during PhD and also during postdoc was motivated by the outer core of the (rapidly-rotating) Earth. Columnar flow structures have also been seen in the spherical simulations of the fluid outer core, that form due to the effect of the Coriolis force. So the question is - are these columns inertial waves or just quasi-two dimensional vortices? This is difficult to answer. One of the reasons is that here the waves may co-exist with turbulent flow and there are other forces due to buoyancy, magnetic field also present. Performing periodic box simulations with one force at a time is a relatively easy way to model the phenomena. Shown below is the periodic box DNS of a layer of buoyancy under rotation, that again shows inertial waves forming vertical columns. Note the (qualitative) similarity with the columns seen in spherical simulations.
The spherical simulation in the center was performed by Prof Binod Sreenivasan. The box simulation was my attempt to model the flow near the equator
Vertical slice of DNS: Columns coming out of the layer of buoyancy
Inertial waves in the core of the Earth and their role in maintaining the magnetic field
Now, you may be wondering if there are low-frequency inertial waves in the spherical simulations? This is precisely the question that led me to perform spherical simulations during my post-doc. This work was funded by the Leverhulme Trust, UK on a grant awarded to Prof Peter Davidson (who was also my PhD supervisor), in collaboration with Prof Uli Christensen and Dr Johannes Wicht at the Max Planck Inst. of solar system research, Gottingen, Germany. The figure below shows that inertial waves are definitely present in the strongly-forced spherical dynamo simulations. The red colour shows the maximum energy, which is present in the inertial wave frequency range. More details are in the research article that can be found here.
'Butterfly' spectrum of fluctuating kinetic energy at two locations in a spherical dynamo simulation: energy is concentrated in the frequency band (-2\Omega, 2\Omega) of inertial waves.
So, the next question that arises is - if the inertial waves exist, what is their role or effect ? Stay tuned ...
Study of incylinder flow using PIV in a cold flow optical test-rig
My MS thesis was on "PIV study of flow due to reciprocating pistons during compression". The first task was due to design & build an optically-transparent engine-like setup (for cold flow) almost from scratch, starting from a Hero-Honda motorbike crankshaft-piston assembly. This was one of hardest tasks I have ever found myself engaged in. For e.g. maintaining the compression ratio was very difficult due to 'omnipresent' leakages. Once this was complete, I performed Particle Image Velocimetry (PIV) measurements of the flow & investigated the effect of piston bowl on the flow (see images below).
Hero Honda crankshaft-piston assembly
The cold-flow optical engine test-rig.
Flow on vertical planes measured using PIV
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