CFD Lab@IITB (Room No. F-29, Mech. Engg. Dept.): Research Gallery

I. Multi-Phase Flows: Computational Multi-Fluid Dynamics (CMFD) Development, Application and Analysis

by D. Datta, Vinesh H. Gada, Saurish Das, Vishesh Aggarwal, Absar Lakdawala, Javed Shaikh and Nagesh Patil

Level Set Method (LSM) is a recent numerical method for capturing transient evolution of interfaces, encountered in various branches of science and engineering. As it was proposed by a mathematician, we were struggling with the physical interpretation of the function used in the method. In the LSM, there are two sets of equations: Navier-Stokes for flow-properties and level-set for interface. In our first work [1], we came up with a physical interpretation and used them in control volume based derivation (commonly used in fluid-mechanics) of the equations used in level set method.

In our second work [2], an improvement in the LSM was proposed to improve the mass-error; the biggest disadvantage of LSM. It was proposed to used finer grid for level-set and coarser grid for Navier-Stokes equations; called as Dual Resolution LSM (DR-LSM). Since the interface-equations are advection equations as compared to non-linear coupled flow-equations, the computational time for the level-set as compared to Navier-Stokes equations are much smaller. The slight increase in the computational cost - due to fine grid for LS equations - for DR-LSM as compared to LSM was envisaged [2] to greatly benefit in terms of substantial improvement the accuracy/mass-error of the result. Thus, a built-in grid globally-refined DR-LSM (one additional grid for level set function in-between two uniformly spaced grid points for velocity/pressure/temperature everywhere in the domain) was proposed for Cartesian [2] and Cylindrical [3] coordinate system; called as Dual-Grid Level-Set Method (DGLSM). It takes slightly more computational time as compared to coarse-grid LSM to achieve a computational accuracy slightly less than that obtained by fine-grid LSM. This was demonstrated for various two-phase flow problems in Cartesian Coordinate [2]; and for two fluid electrodynamic axi-symmetric flow [4]. (Refer ANIMATIONS).

DGLSM was also presented for 2D [2] and 3D [3] film boiling. LSM for casting solidification was developed [5] and a level set based Eulerian–Lagrangian technique was proposed for computation of feed-path - to determine hot-spots. Further modification of DGLSM was presented for two-phase electro-hydrodynamic flow [4] and for non-newtonian two-fluid flow [6]. For contact line motion due to impact dynamics of a droplet on a solid surface, DGLSM was presented recently [7]. Recently, a LSM based parallelization methodology and parallel performance study on five different 3D transient test-cases - corresponding to single/two phase flow, with/without phase change and Cartesian/Cylindrical coordinate system - was presented [8].

LSM based Computational Multi-Fluid Dynamics (CMFD) application and analysis was done for developing smooth-stratified flow in a horizontal channel and a square duct [9]. This was also done for developing oil–water smooth-stratified (SS) and wavy-stratified (WS) flow in a horizontal and inclined plane-channel at various inlet-velocity, inlet-interface-height, inclination-angle, reduced surface-tension and reduced gravity. For smooth-stratified flow in a pipe, a LSM based non-dimensional 3D study is done [11] at various viscosity-ratio, inlet area-fraction of the less-viscous fluid and Reynolds number. For two-phase flow with heat transfer, a DGLSM based study was done [12] for developing two-fluid stratified flow in a plane channel - subjected to various thermal boundary conditions - with and without phase change. DGLSM based CMFD application and analysis was also done for injection of a liquid jet injected upwards into another stationary or co-flowing immiscible liquid [13] at six different combination of the dispersed and continuous fluid and various injection velocity. The above sudy on upward injection of Newtonian jet was extended to downward injection of non-Newtonian jet recently [6]. DGLSM based study was also done for impact-dynamics of bouncing and non-bouncing droplet on superhydrophobic substrates was also studied recently [7]. DGLSM based 2D transient simulation of saturated pool film-boiling on horizontal surface was done for single as well as multi-mode film boiling [3, 14]. 3D transient conjugate heat-transfer simulations for film-boiling in horizontal heat generating rod was done [3] and a transition from synchronous to quasi-periodic bubble-release regime - at a certain critical value of Jacob number - was reported. 2D film-condensation under a horizontal plate was simulated and flow transition from dripping to jetting mode was presented, with increasing degree of sub-cooling of the plate [15]. (Refer ANIMATIONS).

1. Vinesh H. Gada and Atul Sharma, On Derivation and Physical-Interpretation of Level Set Method based Equations for Two-Phase Flow Simulations]], Numerical Heat Transfer-B, Vol. 56, pp. 307-322, 2009.
2. Vinesh H. Gada and Atul Sharma, On a Novel Dual-Grid Level-Set Method for Two-Phase Flow Simulation, Numerical Heat Transfer-B, Vol. 59, 26–57, 2011.
3. Vinesh H Gada, A Novel Level-Set based CMFD Methodology in 2D/3D Cartesian and Cylindrical Coordinates and its Application for Analysis of Stratified flow and Film Boiling. Ph.D Thesis, Mech. Engg., IIT Bombay Mumbai, 2012.
   1. Absar M. Lakdawala, Vinesh H. Gada and Atul Sharma, On Dual Grid Level-Set Method for Computational-Electro-Multi-Fluid-Dynamics Simulation, In-Press, Numerical Heat Transfer-B, 2014a.
4. Mayur Sutaria, Vinesh H. Gada, Atul Sharma and B. Ravi, Computation of Feed-paths for Casting Solidification using Level-Set-Method, Journal of Materials Processing Technology, Vol. 212, pp.1236-1249, 2012.
5. Absar M. Lakdawala, Rochish Thaokar and Atul Sharma, Break-up of a Non-Newtonian Jet Injected Downwards in a Newtonian Liquid, Sadhna - Academy Proc. in Engg. Sciences Under-Review, 2014b.
6. Nagesh D. Patil, Atul Sharma and Rajneesh Bhardwaj, Level set method based simulations on impact-dynamics of bouncing and non-bouncing droplet on superhydrophobic substrates, Proc. 5th Int. and 41st National Conf. on FMFP, IIT Kanpur, Under-Review, 2014.
   1. Vishesh Aggarwal, Vinesh H Gada and Atul Sharma, Parallel Computation of 3D Transient Two-Phase Flow, using Level-Set Method, Numerical Heat Transfer-B, Vol. 63, pp. 327–356, 2013.
7. D. Datta, Vinesh H. Gada and Atul Sharma, Analytical and Level Set Method Based Numerical Study for Two-Phase Stratified Flow in a Plane Channel and a Square Duct, Numerical Heat Transfer-A, Vol 60(4), pp. 347-380, 2011.
8. Vinesh H. Gada and Atul Sharma, Analytical and Level-Set Method based Numerical Study on Oil-Water Smooth/Wavy Stratified-Flow in an inclined Plane-Channel, International Journal of Multiphase Flow, Vol. 38, pp. 99-117, 2012.
9. Saurish Das, Vinesh H. Gada and Atul Sharma, Analytical and Level-Set Method Based Numerical Study for Two-Phase Stratified Flow in a Pipe, In-Press, Numerical Heat Transfer-A, 2014.
   1. Vinesh H. Gada, D. Datta and Atul Sharma, Analytical and Numerical Study for Two-Phase Stratified-Flow in a Channel subjected to different Thermal Boundary Conditions, International Journal of Thermal Sciences, Vol. 71, pp. 88-102, 2013.
   2. Absar M. Lakdawala, Vinesh H. Gada and Atul Sharma, A Dual Grid Level Set Method based Study of Interface-Dynamics for a Liquid Jet Injected Upwards into another Liquid, International Journal of Multiphase Flow, Vol. 59, pp. 206–220, 2014c.
   3. Vinesh H. Gada and Atul Sharma, Simulation of Multi-Mode Film Boiling using Level-Set Method, Proc. of ASME International Mechanical Engineering Congress and Exposition, Florida, Orlando, USA, IMECE2009-11161, 2009.
   4. Vishesh Aggarwal, Vinesh H. Gada, Atul Sharma, Dripping-Jetting Transition during Film Condensation on the underside of a Horizontal Plate, Proc. 39th National Conference on FMFP, SVNIT Surat, Paper ID 164, 2012.

II. Stationary and Moving Bluff-Body Flows: CFD Development, Application and Analysis

by Sachin B. Paramane, Kaushal Prasad and Mukul Srivastava

A Multi-block structured finite volume method based NS solver was developed and effect of various convection schemes was studied [1]. The code is used for unconfined [2-4] and channel-confined [5] flow and heat transfer across a rotating circular cylinder. For the cylinder maintained at constant-wall-temperature [2] and constant heat flux [3], the heat transfer is discussed with the help of heat-lines; proposed for the first time for complex geometry CFD problems. Under the influence of cross-stream buoyancy [4], origin of secondary frequency with the shedding of vortex-pair of two different sizes alternatively is reported at Re=40 and 100. Rotating and channel-confinement is found to have stabilizing effect on the flow [5]. Positive as compared to negative eccentricity - in the position of cylinder in a channel- is found to have more stabilization effect, for counter-clockwise rotating cylinder [6].

The physical principles underlying the extraordinary mobility of swimming and flying animals have been the subject of years of research and there is still much that is not understood. Fishes are smart swimmers which use jet-stream propulsion thereby achieving higher propulsive efficiency as compared to man made machines. The maneuverability and efficiency of fish is inspiring new styles of propulsion and maneuvering in Autonomous Underwater Vehicles (AUVs) for applications such as under-sea exploration and environmental monitoring. The unresolved issues pertain to the mechanisms of propulsion and the mechanical efficiency of self-propelling organisms. Experimental approaches are very difficult, since instrumenting these animals often disrupts the behavior of interest. An opportunity exists to bring modern numerical methods in fluid dynamics to bear on these problems. With this motivation, a level set based immersed boundary method was proposed and an in-house code was developed as well as tested for various moving boundary problems [7]. The code is used for CFD application and analysis of flish like locomotion. 2D simulations are done [8] for flow generated by translating and undulating fish-like body - modeled as NACA 0012 hydrofoil. Shape of hydrofoil needs to be transformed into fish-like body by adding time varying undulations at various X locations from the head of hydrofoil along the axis. A detailed parametric investigation - for various flow, geometric as well as locomotion governing flow parameters - is under-progress for the CFD simulation on hydrodynamics of single as well as multiple (tandem, side-by-side and school arrangement) fish like locomotion (Refer ANIMATIONS).

1. Sachin B. Paramane and Atul Sharma, Consistent Implementation and Comparison of FOU, CD, SOU and QUICK Convection Schemes on a Square, Skewed, Trapezoidal and Triangular Lid Driven Cavity Flow, Numerical Heat Transfer-B,Vol. 54, pp. 84-102, 2008.
2. Sachin B. Paramane and Atul Sharma, Numerical Investigation of Heat and Fluid Flow across a Rotating Circular Cylinder Maintained at a Constant Temperature in 2-D Laminar Flow Regime, International Journal of Heat and Mass Transfer, Vol. 52, pp. 3205-3216, 2009.
3. Sachin B. Paramane and Atul Sharma, Heat and Fluid Flow across a Rotating Cylinder Dissipating Uniform Heat Flux in 2-D Laminar Flow Regime, International Journal of Heat and Mass Transfer, Vol. 53, pp. 4672–4683, 2010.
4. Sachin B. Paramane and Atul Sharma, Effect of Cross-Stream Buoyancy and Rotation on the Free-Stream Flow and Heat Transfer across a Cylinder, International Journal of Thermal Sciences, Vol. 49, pp. 2008-2025, 2010.
5. Kaushal Prasad, Sachin B. Paramane, Amit Agrawal and Atul Sharma, Effect of Channel-Confinement and Rotation on the Two-Dimensional Laminar Flow and Heat Transfer across a Cylinder, Numerical Heat Transfer-A, Vol 60(8), pp. 699-726, 2011.
   1. Kaushal Prasad, Amit Agrawal and Atul Sharma, Poiseuille Flow across an Eccentrically-Con.fined Stationary/Rotating Cylinder, Ocean Engineering, Vol. 73, pp. 41-54, 2013.
6. Mukul Shrivastava, Amit Agrawal and Atul Sharma, A Novel Level-Set Based Immersed Boundary Method for CFD Simulation of Moving Boundary Problems, Numerical Heat Transfer-B, Vol. 63, pp. 304–326, 2013a. AWARDED **Computational Talent Prize** for the year 2013 given by SHELL India.
7. Mukul Srivastava, Amit Agrawal and Atul Sharma, CFD study on Hydrodynamics of Fish-like Undulating Foil using a Novel Level-Set Based Immersed Boundary Method, Proc. 40th National Conference on FMFP, NIT Hamirpur, Paper ID 283, 2013b.