• Majee S, Ray RK., Majee AK. A New Non-linear Hyperbolic-parabolic Coupled PDE Model for Image Despeckling. IEEE Transactions on Image Processing (IEEE), 2022 (Accepted).
• Kumar A, Ray RK.. Shape effect of nanoparticles and entropy generation analysis for magnetohydrodynamic flow of ( ) hybrid nanomaterial under the influence of Hall current. Indian Journal of Physics (Springer), 2022 (Accepted).
• Pankaj, Ray RK.. Numerical Study on Combined Convection Heat Transfer Flow Problem in a Porous Corrugated Enclosure. Heat Transfer (Wiley), DOI: 10.1002/htj.22449, 2022.
• Kumar A, Ray RK., Sheremet MA. Entropy generation on double-diffusive MHD slip flow of nanofluid over a rotating disk with non-linear mixed convection and Arrhenius activation energy. Indian Journal of Physics (Springer), 96(2):525-541, 2022.
• Ray RK., Haty A, Kumar A. Heat transfer past rotationally oscillating circular cylinder heated with time-periodic pulsating temperature in a uniform flow. Heat Transfer (Wiley), DOI: 10.1002/htj.22426, 2021.
• Majee S, Jain SK, Ray RK., Majee AK. A fuzzy edge detector driven telegraph total variation model for image despeckling. Inverse Problems and Imaging (AIP), DOI: 10.3934/ipi.2021054, 2020.
• Kumar A, Ray RK., Raha S. Impact of inlet shear on unsteady boundary layer separation from two square cylinders in tandem arrangement. Journal of the Brazilian Society of Mechanical Sciences and Engineering (Springer), 43(12): 1-24, 2021.
• Kumbhakar M, Ray RK., Chakraborty SK, Ghoshal K, Singh VP. Mathematical modelling of streamwise velocity profile in open channels using Tsallis entropy. Communications in Nonlinear Science and Numerical Simulation (Elsevier), 94: 105581, 2021.
• Mittal HVR, Ray RK., Gadelha H, Patil DV. A coupled immersed interface and level set method for simulation of interfacial flows steered by surface tension. Experimental and Computational Multiphase Flow (Springer), 3(1): 21-37, 2021.
• Kumbhakar M, Ray RK., Ghoshal K, Singh VP. On the role of Tsallis entropy index for velocity modelling in open channels. Physica A: Statistical Mechanics and its Applications (Elsevier), 557: 124901, 2020.
• Majee S, Jain SK, Ray RK., Majee AK. On the development of a coupled nonlinear telegraph-diffusion model for image restoration. Computers & Mathematics with Applications (Elsevier), 80(7): 1745-1766, 2020.
• Kumar A, Ray RK.. A Structural Bifurcation Analysis of Flow Phenomenon for Shear Flow Past an Inclined Square Cylinder: Application to 2D Unsteady Separation. Fluid Dynamics (Tsinghua University Press), 55: 391-406, 2020.
• Jain SK, Ray RK.. Non-linear diffusion models for despeckling of images: achievements and future challenges. IETE Technical Review (Taylor & Francis), 37(1): 66-82, 2020.
• Kumar A, Ray RK.. Theoretical understanding of unsteady flow separation for shear flow past three square cylinders in vee shape using structural bifurcation analysis. Computational and Applied Mathematics (Springer), 39: 177, 2020.
• Majee S, Ray RK., Majee AK. A Gray Level Indicator-Based Regularized Telegraph Diffusion Model: Application to Image Despeckling. SIAM Journal on Imaging Sciences (SIAM), 13(2): 844-870, 2020.
• Kumar A, Ray RK.. Structural bifurcation analysis of vortex shedding from shear flow past circular cylinder. Computational and Applied Mathematics (Springer), 38(3): 121, 2019.
• Jain SK, Kumar A, Thakur M, Ray RK.. Proximal Support Vector Machine-Based Hybrid Approach for Edge Detection in Noisy Images. Journal of Intelligent Systems (De Gruyter), 29(1): 1315-1328, 2019.
• Jain SK, Ray RK., Bhavsar A. A Non-Linear Coupled Diffusion System For Image Despeckling and Application to Ultrasound Images. Circuits, Systems, and Signal Processing (Springer), 38(4): 1654-1683, 2019.
• Kumar A, Ray RK.. Structural Bifurcation Analysis of Unsteady Flow Separation for Shear Flow Past an Array of Three Square Cylinders in Series. Mathematical Sciences International Research Journal (IMRF), 7(2): 15-22, 2018.
• Tyagi S, Abbas S, Meherrem S, Ray RK.. Time-delay-induced instabilities and Hope bifurcation analysis in 2-neuron network model with reaction-diffusion term. Neurocomputing (Elsevier), 313: 306-315, 2018.
• Mittal HVR, Ray RK.. Solving Immersed Interface Problems Using a New Interfacial Points Based Finite Difference Approach. SIAM Journal of Scientific Computing 40(3): A1860-A1884, 2018.
• Mittal HVR, Qasem MA, Ray RK.. Locked-on vortex shedding modes from a rotationally oscillating circular cylinder. Ocean engineering (Elsevier), 146: 324-338, 2017.
• Mittal HVR, Ray RK., Qasem MA. A numerical study of initial flow past an impulsively started rotationally oscillating circular cylinder using a transformation-free HOC scheme. Physics of Fluids (AIP), 29(9): 093603, 2017.
• Tyagi S, Abbas S, Ray RK.. Stability and Bifurcation analysis of Cellular Neural Networks with Discrete and Distributed delays. Proceedings of the National Academy of Sciences, India Section A: Physical Sciences (Springer), 1-17, 2017.
• Ray RK., Kumar A. Numerical study of shear rate effect on unsteady flow separation from the surface of the square cylinder using structural bifurcation analysis. Physics of Fluids (AIP), 29(8): 083604, 2017.
• Kumar A, Ray RK.. A Numerical simulation of shear flow past two equal sized square cylinders arranged in parallel at Re=500. AIP Conf. Proc., 1863:490003-1-490003-4, 2017.
• Mittal HVR, Ray RK.. Solving Moving Interface Problems Using a Higher Order Accurate Finite Difference Scheme. AIP Conf. Proc., 1863:490002-1-490002-4, 2017.
• Jain SK, Ray RK.. Edge Detectors Based Telegraph Total Variational Model for Image Filtering. Information Systems Design and Intelligent Applications. Advances in Intelligent Systems and Computing (Springer), 433:119-126, 2016.
• Mittal HVR, Kalita JC, Ray RK.. A class of finite difference schemes for interface problems with an HOC approach. International Journal for Numerical Methods in Fluids (Wiley), 82:567-606, 2016.
• Ray RK, Kalita JC. Higher-Order-Compact Simulation of Unsteady Flow Past a Rotating Cylinder at Moderate Reynolds Numbers. Computationl and Applied Mathematics (Springer), 35(1):219-250, 2016.
• Mittal HVR, Ray RK.. A Cartesian Grid Method for Solving Stokes Equations with Discontinuous Viscosity and Singular Sources. Advanced Computing and Communication Technologies. Advances in Intelligent Systems and Computing (Springer), 452:315-323, 2016.
• Kumar A, Ray RK.. Higher order compact numerical simulation of shear flow past inclined square cylinder. Advanced Computing and Communication Technologies. Advances in Intelligent Systems and Computing (Springer), 452:305-313, 2016.
• Mittal HVR, Ray RK.. A New Direction To Higher Order Compact Scheme For Solving Immersed Interface Problems. Mathematical Sciences International Research Journal (IMRF), 4(1):51-54, 2015.
• Tyagi S, Abbas S, Ray RK.. Stability Analysis of an Integro Differential Equation Model of Ring Neural Network with Delay. Mathematical Analysis and its Applications (Springer), 143:37-49, 2015.
• Kumar A, Ray RK.. Numerical Study of Shear Flow Past a Square Cylinder at Reynolds Numbers 100, 200. Procedia Engineering (Elsevier), 127:102-109, 2015.
• Mittal HVR, Ray RK.. An HOC Based Immersed Interface Scheme for Uniform Flow Past a Circular Cylinder. Procedia Engineering (Elsevier), 127:244-249, 2015.
• Jain SK, Ray RK., Bhavsar A. Iterative Solvers for Image Denoising with Diffusion Models: A Comparative Study. Computers and Mathematics with Applications (Elsevier), 70:191-211, 2015.
• Jain SK, Ray RK.. A Non-Linear Diffusion based Partial Differential Equation Model For Noise Reduction in Images. Information Systems Design and Intelligent Applications. Advances in Intelligent Systems and Computing (Springer), 340:429-438, 2015.
• Jain SK, Ray RK., Bhavsar A. A Comparative Study of Iterative Solvers for Image De-noising. Proceedings of the 3rd International Conference on Frontiers of Intelligent Computing: Theory and Applications (FICTA). Advances in Intelligent Systems and Computing (Springer), 328:307-314, 2015.
• Mittal HVR, Ray RK. A Transform Free Higher Order Compact Finite Difference Scheme for Simulating the Flow behind a Rotationally Oscillating Circular Cylinder at Reynolds number 500. Applied Mechanics and Materials, 367:126-131, 2013.
• Shi Yu-e, Ray RK, Nguyen KD. A Projection Method-based model with the exact C-property for shallow-water flows over dry and irregular bottom using unstructured finite-volume technique. Computers & Fluids (Elsevier), 76:178-195, 2013.
• Ray RK, Mittal HVR. A Transform-Free HOC Scheme for Incompressible Viscous Flow past a Rotationally Oscillating Circular Cylinder. World Academy of Science, Engineering and Technology. International Journal of Physical and Mathematical Sciences, 6(12):1763-1769, 2012.
• Ray RK. A Transformation-free HOC Scheme for Incompressible viscous Flow Past a Rotating and Translating Circular Cylinder. Journal of Scientific Computing (Springer), 46(2):265-293, 2011.
• Ray RK, Nguyen KD. An Unstructured Finite-volume Technique for Shallow-water Flows with Wetting and Drying Fronts. World Academy of Science, Engineering and Technology, 71:682-687, 2010.
• Ray RK, Kalita JC. A transformation-free HOC scheme for incompressible viscous flows on nonuniform polar grids. International Journal for Numerical Methods in Fluids (Wiley), 62:683-708, 2010.
• Kalita JC, Ray RK. A transformation-free HOC scheme for incompressible viscous flow past an impulsively started circular cylinder. Journal of Computational Physics (Elsevier), 228:5207-5236, 2009.
• Ray RK, Kalita JC, Dass AK. An efficient HOC scheme for transient convection-diffusion-reaction equations with discontinuous coefficients and singular source terms. Proc. Appl. Math. Mech., 7(1):1025603-1025604, 2007.

• Kumar A, Ray RK.. Numerical simulation of flow around square cylinder with an inlet shear in a close channel. Applications of Fluid Dynamics. Lecture Notes in Mechanical Engineering, pp.: 297-304, 2017.
• Mittal HVR, Ray RK. A New Direction to Higher Order Compact (HOC) Scheme for Solving Immersed Interface Problems. In: Multiphase Flows with Phase Change Challenges and Opportunities, IIT Hyderabad, India.
• Mittal HVR, Ray RK. An efficient higher order accurate finite difference scheme for solving two dimensional elliptic equations with discontinuities. In International Congress of Mathematicians (ICM); Seoul, South Korea, 2014.
• Jain SK, Ray RK. A comparative study of iterative solvers for image de-noising using Crank-Nicolson scheme. In International Congress of Mathematicians (ICM); Seoul, South Korea, 2014.
• Ray RK, Mittal HVR. Numerical study of transition flows over a rotationally oscillating circular cylinder. In International Congress of Mathematicians (ICM); Seoul, South Korea, 2014.
• Nguyen KD, Ray RK, Pham Van Bang D. Modeling of Sediment Transport and Turbidity Maximum in the Gironde Estuaries (France) by Single- and Two-Phase Approaches. In: The 10th Int. Conf. on Hydroscience and Engineering (ICHE); Orlando, USA, 2012.
• Nguyen KD, Ray RK, Pham Van Bang D. Modeling of Sediment Transport and Turbidity Maximum in the Gironde Estuaries (france) by a Two-Phase Non-Hydrostatic Model. In: American Geophysical Union, Fall Meeting; San Francisco, USA, 2012.
• Ray RK, Kalita JC. An efficient higher order accurate scheme for two-dimensional Immersed Interface problems. In: Third International Conference on MetaComputing (ICoMeC), Bhubaneswer, India, 2012.
• Nguyen KD, Ray RK. An Unstructured Finite-volume Technique for Shallow-water Flows with Wetting and Drying Fronts. In: ASME-JSME-KSME 2011 Joint Fluids Engineering Conference (AJK2011-FED), Hamamatsu, Japan, 2011.
• Ray RK. New findings on Alpha-Beta Phenomena for Unsteady Flow Past an Impulsively Started Circular Cylinder. In: IUTAM Symposium on Bluff Body Flows (Blubof); IIT Kanpur, India, 2011.
• Nguyen KD, Levy F, Ray RK, Pham Van Bang D. Modeling of Sediment Transport and Turbidity Maximum in the Gironde Estuaries (France) by Single- and Two-Phase Approaches. In: River, Coastal and Estuarine Morphodynamics (RCEM), Beijing, China, 2011.
• Levy F, Ray RK, Nguyen KD and Pham Van Bang D. Two-phase modelling for turbidity maximum transport in the Gironde Estuary (France). In: Two-pHase modElling for Sediment dynamIcS (THESIS), Paris, France, 2011.
• Ray RK, Kalita JC, Dass AK. An efficient HOC scheme for 1D elliptic equations with discontinuous coefficients and singular source terms using nonuniform space grids. In: Indo-Australian Workshop and Symposium in CFD, IIT Roorkee, India, 2007.

• Development of an efficient numerical method for solving stochastic Partialdifferential equation and its application to turbulent flow analysis; Sponsored by SERB (DST).
  Duration: 3 years (08/2018 - 07/2021); Project Value: 20.09 Lakh.
• Modelling of Contaminated sediment transport in lake/river; Sponsored by BRNS (DAE).
  Duration: 3 years (07/2014 - 10/2018); Project Value: 21.07 Lakh (with Dr. O. P. Singh (Co-PI)).
• Development of Higher Order Accurate Numerical Schemes for Elliptic Equations with various Discontinuities and its Application to Immersed Interface Problems ; Sponsored by NBHM (DAE).
  Duration: 3 years (01/2015 - 01/2018); Project Value: 2.99 Lakh.
• Development of a class of Higher Order Compact (HOC) Finite Difference schemes and its application to Linear Shear Flows; Sponsored by SERB (DST).
  Duration: 3 years (02/2014 - 02/2017); Project Value: 13.32 Lakh.
• Higher Order Compact (HOC) Finite Difference scheme for Elliptic Equations with Discontinuous Coefficients and Singular Source Terms; Sponsored by IIT Mandi (Seed Grant) .
  Duration: 3 years (2011 - 2014); Project Value: 5.00 Lakh.

Teaching at IIT Mandi

• MA-101: Mathematics I.
• MA-201: Mathematics III.
• IC-110: Engineering Mathematics.
• IC-111: Linear algebra.
• IC-150P: Computation for Engineers Lab.
• CS-203: Discrete Mathematics.
• MA-607: Numerical Analysis.
• MA-608: Computational Fluid Dynamics.
• MA-609: Numerics of PDEs.
• MA-709: Numerical Linear Algebra.
• MA-565: Numerical Methods in Quantitative Finance
• MA 555: Introduction to PDEs for Engineers
• IC-201P: Design Practicum
• MA-514: Computer Programming
• MA-514P: Computer Programming Lab
• MA-523: Numerical Analysis
• IC210: Probability, Statistics and Random Processes
• MA524: Probability & Statistics

Graduated Ph.D. Students

• Hari Vansh Rai Mittal (Registration No.: D11023, Thesis defended on July, 2016)
• Thesis title: A CLASS OF HIGHER ORDER ACCURATE SCHEMES FOR FLUID INTERFACE PROBLEMS
(Currently working as an Assistant Professor at IIT Palakkad.)
• Subit Kumar Jain (Registration No.: D12070, Thesis defended on June, 2018)
• Thesis title: A CLASS OF NON-LINEAR COUPLED PARTIAL DIFFERENTIAL EQUATION BASED MODELS FOR IMAGE RESTORATION WITH ITS NUMERICAL REALIZATION
(Currently working as an Assistant Professor at NIT Hamirpur.)
• Atendra Kumar (Registration No.: D14033, Thesis defended on December, 2018)
• Thesis title: UNSTEADY FLOW SEPARATION FROM THE SURFACE OF SOLID CYLINDERS IN LAMINAR SHEAR FLOW: A STRUCTURAL BIFURCATION ANALYSIS
(Currently working as an Assistant Professor at NIT Srinagar.)
• Sudeb Majee (Registration No.: D15028, Thesis defended on December, 2020)
• Thesis title: DEVELOPMENT AND ANALYSIS OF A CLASS OF TELEGRAPH-DIFFUSION MODELS: APPLICATION TO IMAGE RESTORATION
(Currently working as a Post-Doctoral fellow in Umea University, Sweden.)

Ongoing Ph.D. Students

• Amarjit Haty (Registration No.: D16022)
• Pankaj (Registration No.: PTD1601)
• Ashwani (Registration No.: D19022)
• Mandira Samadder (Registration No.: D19025)
• Kajal Mittal (Registration No.: D20073)

• Achieved First class 2nd position in M.Sc. (in Mathematics).
• Achieved First class 2nd position in B.Sc. (in Mathematics).
• 96.19 percentile (57th all India rank) in GATE 2004 (in Mathematical Sciences).
• National Merit Scholarship for 10+2 Examination.
• National Merit Scholarship for B.Sc. (in Mathematics) Examination.
• University Merit Scholarship Visva-Bharati University, India (1998, 2000–2003).
• Gold Medal in Cricket in the 21st Inter IIT Staff Sport Meet, IIT Guwahati, 2013.
• Included in Marquis Who's Who in the World 2015 - 32nd Edition.

As a Faculty

• Chairman, JEE Cell, IIT Mandi, India (2021-present).
• Chairman, Commercial Establishment Committee, IIT Mandi, India (2021-present).
• Chairman, Student Affairs Panel, IIT Mandi, India (2017-present).
• Chairman, Advisory Board, Hospitality and Guest House Service, IIT Mandi, India (2017-18).
• Coordinator, M.Sc. in Applied Mathematics program, IIT Mandi, India (2015-17).
• Sports Advisor, IIT Mandi, India (2015-17).
• Coordinator, Hiking and Trekking Club, IIT Mandi, India (2011-14).
• Warden, Nako Hostel, IIT Mandi, India (2011-14).
• Chairman, Transport Advisory Board, IIT Mandi, India (2016).
• Chairman, Student/Hostel Related Purchases committee, IIT Mandi, India (2013-14).
• Chairman, PhD admission committee in Mathematics, IIT Mandi, India (Dec.-2012, July-2013, July-2014).
• Co-Advisor, Institute Transport Committee, IIT Mandi, India (2015).
• Faculty In-charge, Staff Contingents for Inter-IIT Staff Sport Meet, IIT Mandi, India (2013-18).

As a Students

• Student Representative, Departmental Postgraduate Programme Committee (DPPC), Department of Mathematics, Indian Institute of Technology Guwahati, India, (2005–2008).
• Member, American Mathematical Society (AMS).
• Member, Society for Industrial and Applied Mathematics (SIAM).
• Cultural Secretary, Siang Hostel, Indian Institute of Technology Guwahati, India (2006-2007).
• Member, Mess Management Committee, Siang Hostel, Indian Institute of Technology Guwahati, India(2004-2005).
• StudentWarden, Shantishree Boys’ Hostel, Visva-Bharati University, India (2002–2003).
• Mess Convenor, Nanda Sadan Boys’ Hostel, Visva-Bharati University, India (2000–2001).