Research
1. Blood flow modeling in image-based model of Acute Ischemic Stroke patients.
Acute ischemic stroke (AIS) is a life-threatening medical condition that occurs when a blood clot becomes lodged in the cerebral vasculature and obstructs blood flow to the brain. More research is needed to elucidate the underlying causes and treatment of AIS, which is complicated due to the large variability in cerebral artery anatomy among patients. A better understanding of cerebral hemodynamics and clot migration, in particular, may offer better insight into how occlusive clots become lodged. The objective of this work is to establish a computational model for simulating the hemodynamics and the migration and lodging of blood clots in complex anatomical models of the cerebral vasculature and to validate the predictions by comparing with in vitro experiments.
2. Influence of Glottal Motion on Inhalation Therapy Outcomes
Inhalation therapy is the first line of drug delivery for the treatment of respiratory diseases including worldwide leaders of morbidity and mortality such as asthma and Chronic Obstructive Pulmonary Disease (COPD). Despite its clinical prevalence, inhalation therapy remains appallingly inefficient with low deposition efficiency rates (typically well under 50% of an inhalation dose). The success of depositing inhalation aerosols to local airway sites of action revolves around a multitude of parameters including the delivery devices, inspiratory maneuvers, lung anatomy, etc. In this context, the extra-thoracic (mouth–throat) airways are known to have a major influence on aerosol delivery to the proximal and peripheral intra-thoracic airways. In particular, the glottis, defined by the vocal-fold aperture, causes upper airways to dramatically narrow down to a minimal cross section; an anatomical feature that has notorious outcomes on aerosol deposition and effectively acts as a “screen” or filter via particle inertial impaction. In view of past research on glottis effect on airflows, most geometrical models either consider a simple tube-like upper airway with a more elaborate glottal opening (in terms of its shape or dynamics) or instead have considered a more realistic upper airway model with a circular glottis opening. Both upstream and downstream, the geometry is likely to affect the effect of glottis opening on jets and associated flow patterns. In addition, static glottis and steady or quasi-steady flows have often been assumed in previous in vitro and numerical works. Our objective is to quantify how the glottis motion and cyclic flow affect the respiratory dynamics, individually or as a combination, and subsequently map such factors on inhalation aerosol transport outcomes.
Glottis movement
3. Dynamics of droplet displacement and spreading on solid surface
Droplet moving on a surface has a wide area of scope in industrial as well as in engineering applications. The present work focuses on exploring the complex physics associated with dynamics of coalescence, elongation and spreading on the surface having various types of wetting conditions (e.g., hydrophobic, hydrophilic, mixed and superhydrophobic wetting). In the scenarios like water transport in gas diffusion layer of PEM fuel cell, enhanced oil recovery and droplet movement in ink-jet printings, it is necessary to elucidate the effect of capillarity-wettability interaction on droplet movement. This research also investigates the dynamics of droplet displacement on rough surface which is modelled in the form of grooves on the surface.
4. Droplet falling in a Partially Obstructed Confinement
This work is carried out to analyse the droplet dynamics due to capillarity-wettability interaction through a partially obstructed channel confinement. To explore the dynamic behavior of droplet motion past an obstruction, the effects of modified capillary number and surface wettability, including obstruction size and architecture, are elucidated. In this work, a single spherical obstruction, and different spherical agglomerate structures have been considered. The mesoscale simulations exhibit interesting two-phase flow physics and pattern formations due to droplet pinching, break up, and surface adherence owing to the underlying wettability-capillarity characteristics. This study further reveals an interesting trade-off, between the time required for the bulk droplet fluid to pass by and/ or through the obstruction and the fraction of droplet fluid volume adhering to the surface, depending on the combination of the modified capillary number and surface wettability.
5. Immiscible fluid flow through porous architecture
Understanding the displacement dynamics in capillarity driven two-phase flow in packed bed architectures is of fundamental importance. In this work, the role of mesoscale physics due to the underlying capillarity-wettability interaction on the two-phase flow in a sphere-packed architecture is presented. The influence of different pore surface wettability, porosity and pressure gradient on the two-phase flow behavior has been studied. The mesoscale study exhibits interesting pattern formations due to the invasion of a non-wetting fluid and surface adherence owing to the underlying wettability-capillarity characteristics. The emergence of finger like invasion pattern in a hydrophobic architecture is observed while a stable fluid front predominates in a hydrophilic structure. This study further reveals that a hydrophilic architecture is prone to elevated saturation limit for the invading fluid, while a larger pressure gradient can promote pronounced finger-like patterns.
6. Enhancement of heat transfer in closed enclosures
In the present study, natural convection inside a two-dimensional right-angled triangular enclosure having three undulations on the left wall filled with porous media has been studied numerically. In most of the engineering application we can see the undulated geometry e.g., regenerative heat exchanger. The other applications of natural convection heat transfer in porous media are also found in solar power collectors, air saturated fibrous insulation material surrounding a heated body, pollutant dispersal in aquifers, storage of nuclear waste in deep geological repositories and heat loss from underground energy storage systems. Effect of Rayleigh number, Darcy number and undulations on the heat transfer and fluid flow has been analyzed using finite difference method and stream function-vorticity formulation.
