News

• Views from Dhanbad on HPCL:
18th October, 2020: On the personal front, yes, the move has been made to IIT (ISM) Dhanbad! Having spent a fortnight in quarantine, Soma, Aditi and I have started our new chapter in Dhanbad and begun our respective new innings. As we foresaw it, HPCL is marching on few aspects of research. Apart from our work on exa-scale computing with teams from Bengaluru, Kalyanpur and Dhanbad, we have completed a new experiment. When the world was wrestling with closedown due to the corona virus -- to keep our spirits high, we teamed up with Prof. Pierre Sagaut and invited some of our HPCL stalwarts to write a review paper on GSA. This is achieved and we will try to take it forward. This is truly an on-line effort and it was not very easy, as this is going to be a state of art on the subject.

We are also going to take part in an effort instituted by Physics of Fluids to pay a tribute to Prof. Frank M. White on his 88th Anniversary. We are planning to submit some of our best research efforts to suit the occasion. Given our great association with Prof. White over last fifteen years (which is well documented in his classic book on Fluid Mechanics) began with flow past bluff bodies and Magnus-Robins effect, we will raise the topic to another level. We will use Taylor-Proudman theorem and investigate the conundrum of dimensionality in fluid flow.

    • Last posting from HPCL: On 6th September, 2020: After a prolonged association with an institution for thirty years, there is a sense of feeling of liberation. Specially, when it becomes obvious that apart from affecting a small number of individuals, rest of the system happily moving towards oblivion. However, HPCL is marching on in every aspect of research. There was a great M. Tech. thesis defense by Sai Theja on 4th September, 2020. Our contribution on non-uniform compact scheme will now go to another level for flow past arbitrary deforming bodies! Applying to specific cases will complete the research part.

We had a great get together using Google-meet on 30th August. The participation from many corners of the globe is a demonstration of familial kinship we enjoy at HPCL, even if we are ten-thousand miles apart and we have separated almost ten to fifteen years ago. There was a feeling that HPCL has done well to chart its own course, despite unethical pressures coming from the peer group. Slowly the tide is turning and our alumni are making their presence felt with mark of individuality and creativity. Everyone highlighted to trust more on individual integrity and demonstration of character.

HPCL is about to announce the work that takes the error due to parallelization disappear from computing. That is, the code will not feel the use of parallelization, with error as one expects to get for sequential computing. We will not have overlap among sub-domain boundaries and the error at subdomain boundary will be made to disappear using GSA.

25th August, 2020: We wait and wait for the life time thinking about the coming departure day from a place where you have spent three decades. Today is also a successful day with Jyothi Kumar Puttam making a very good presentation for the state of the art seminar, related to his PhD plan. This follows the successful seminar by Suman on 22nd August. As both of them are from NAL, we expect outstanding thesis by them, supporting each other and I will be with them from a distant location.

    • A new book is now in an advanced stage. Proof reading completed and the book is titled as, "Transition to Turbulence: A Dynamical System Approach to Receptivity". This was the mission with which we arrived in IIT K in 1990, and the timing of publishing the book cannot be more apt! We have solved the problem that lasted for 150 years! The book is a testimony to that effort. As the author, I feel fortunate to pen this down, which is executed with the dour spirit of HPCL by many over the last three decades. Final touches provided by Prasanna, Suman and Aditi gives it an appearance of a nice job done!

    • Packing old papers/ books and reports, I came across this entry in one of my old diary. My hobby of collecting nice topical quotes is regarding TESLA (not the car!) -- the great scientist. One evening he apparently recited these stanzas from Goethe's Faust while walking in Budapest (1882), thinking about the principles of AC induction motor:

The glow retreats, done is the day of toil;
It yonder hastes, new fields of life exploring
Ah, that no wing can lift me from the soil
Upon its track to follow, follow soaring

A glorious dream! Through now the glories fade.
Alas! the wings that lift the mind no aid
of wings to lift the body can bequeath me!

25th July: Time is approaching for the end of an era for me at Kanpur, a very challenging place, where I founded the HPCL. HPCL will remain alive in spirit for everyone who have spent a short time as team member. Prof. Rakesh Kumar Mathpal is taking over HPCL and we welcome a caring, observant faculty. Students of HPCL will benefit from his guidance.

16th July, 2020: Yesterday was one of our happiest days to see our daughter, Aditi, defend her PhD thesis from Univ. of Cambridge, UK very successfully. This is one of the major works on flow transition and turbulence. In pursuing the work, she interacted with HPCL and co-authored many of her works. Effort to understand free stream excitation, as different from wall excitation, has been taken to a significantly advanced level of understanding. The publications from this thesis, has already rekindled interest on similar investigations originally initiated by GI Taylor and JM Kendall. The "success" of Tollmien-Schlichting wave captured the imagination of the fluid dynamicists for the last 80 years! This thesis and associated ongoing work at HPCL will make the receptivity to free stream excitation as a major research topic. She emphasized on methods specifically developed to analyze DNS results based on DME and DETE. One would now hope to see some focused experiments to match the progress made computationally and theoretically in recent times.

7th July, 2020: In these uncertain days, we are all affected physically and mentally. We worked from home, now some of us are back at our desk. But students have left HPCL! Our work on a review paper for GSA is taking concrete shape. Prof. Sagaut is taking part in some major aspects. Manoj brings his ideas on shallow water equation.

Unlike my last musing, I do not wish to sound sad. This is the rule that old must give way to the new. So I wish to see new ideas and spirit. The central values and ethos should be maintained. HPCL will energize the field with new ideas, despite any belligerent or bellicose opposition to changes and ideas. We will remain humble. Our identity is our character, as always.

May, 2020: Momentous changes are inevitable- time has come for me to say Goodbye to HPCL and its members officially from Kalyanpur. We have shown the indomitable spirit of HPCL, and we are dispersed all over! This is not you plan, but the time has come to say goodbye! This is destiny that the academic area in IITK is inaccessible, all the students have left campus, and I have Aditi as company at home to help me with research work. We are writing a review paper on GSA, with Prasanna contributing from home, Yogesh from IIT BBS, Suman from NAL and Aditi supporting many aspects. Manoj has shown up! It makes me nostalgic, writing about different aspects of works done at different times with memories of students flashing by! It transports me back to those days of HPCL in full glory. Hope these thoughts will reach you all! Stay safe and stay well! Pray for your good health!!

    • News from HPCL: 1) Gaurav (Ganeriwal) visited us after sixteen years with his wife and daughter. It was a touching moment, as we laid the theoretical foundation of Scientific Computing pioneered by HPCL together. GSA and Gibbs' phenomenon continue to be of our interest; it was also Gaurav's B. Tech. project! 2) Vijay has joined Columbia Univ. as a faculty member. 3) S. Unnikrishnan has joined the faculty in Florida. 4) Atchyut Srinivas is winner of Star Award performer in Mercedes Benz for his work on optimization. He is also the recipient of "Above and Beyond Award for Setting up Transient method". 5) Sriramakrishnan has joined for post-doc in Switzerland, after his PhD in Texas, USA (6) Pushpender graduated from HPCL and will head to UK for post-doctoral. Prof. Venkat at IITH continues to do pioneering work, as many others are doing in India and abroad. Kamesh is doing great at IIT Madras.

    • The tentative publications in 2019 so far are (Apart from writing and editing two books published by Springer Nature, Singapore and Springer Nature, Switzerland):

1) Error growth and phase lag analysis for high Courant numbers - D. Sharma, S. Amiroudine , A. Erriguible , T. K. Sengupta, Applied Mathematics and Computation, vol. 346 374-384 (2019)

2) Grid sensitivity and role of error in computing a lid-driven cavity problem - V. K. Suman, Siva Viknesh S., Mohit K. Tekriwal, S. Bhaumik, and T. K. Sengupta, Physical Review E, vol. 99, 013305 (2019)

3) Is Tollmien-Schlichting wave necessary for transition of zero pressure gradient boundary layer flow? - P. Sundaram, T. K. Sengupta , and S. Sengupta, Physics of Fluids, vol. 31, 031701 (2019)

4) Vorticity dynamics of the three-dimensional Taylor-Green vortex problem - N. Sharma and T. K. Sengupta, Physics of Fluids, vol. 31, 035106 (2019)

5) Thermodynamic merger of fluctuation theorem and principle of least action: Case of Rayleigh-Taylor instability - S. P. Mahulikar, T. K. Sengupta, Pallavi Rastogi and Nidhi Sharma, J. Non-Equilibrium Thermodynamics, (2019)
https://doi.org/10.1515/jnet-2018-0091

6) Effect of frequency and wavenumber on the three-dimensional routes of transition by wall excitation -- Pushpender Sharma and Tapan Sengupta, Physics of Fluid, 31, 064107 (2019)

7) Role of bulk viscosity on transonic shock wave-boundary layer interaction -- Sahil Bhola, TK Sengupta, Phys. of Fluids, 31(9), 096101 (2019)

8) Direct numerical simulation of vortex-induced instability for zero pressure gradient boundary layer -- Aditi Sengupta, VK Suman, TK Sengupta, Phys. Rev. E 100, 033118 (2019); https://DOI: 10.1103/PhysRevE.100.033118

    • Progress is made in understanding coherent structure detection techniques. Disturbance mechanical energy (DME) and disturbance enstrophy transport equations (DETE) hold the key. These two are based on translational and rotational energy in a flow, as opposed to other techniques which identify vortex via pressure minimum.

With the monograph on "DNS of Wall Bounded Turbulent Flows", T.K. Sengupta and S. Bhaumik have taken the initiative to write down in details on the subject. This case study will act as a guide-book for those interested in learning hands-on!

Two chapters in CISM monograph:
Sengupta T.K., Sharma P.K. - Space-Time Resolution for Transitional and Turbulent Flows. In: Pirozzoli S., Sengupta T. (eds) High-Performance Computing of Big Data for Turbulence and Combustion.

Sengupta T.K., Suman V.K. - Focusing Phenomenon in Numerical Solution of Two-Dimensional Navier–Stokes Equation. In: Pirozzoli S., Sengupta T. K. (eds) High-Performance Computing of Big Data for Turbulence and Combustion. CISM International Centre for Mechanical Sciences (Courses and Lectures), vol 592. Springer, Cham (2019)
DOI https://doi.org/10.1007/978-3-030-17012-7_1

HPCL continues to explain many aspects of FOCUSING - an abrupt numerical meltdown faced in computing! Codes running for long, suddenly blows up in short time is termed FOCUSING. This has been attributed to nonlinear instability, following early works by Phillips and Smagorinsky, while others attributed it to chaos dynamics. Present work follows up work at HPCL to investigate scientific computing for a CEFIPRA project. Global spectral analysis (GSA) was used for scientific computing for: 2D convection equation, diffusion equation, convection-diffusion equation, shallow water equation, KdV equation, bidirectional waves and convection-diffusion-reaction equation. Work on focusing restarted for 3-time level methods with results in AMC (2017) for Adams-Bashforth method. The following papers in Computers and Fluids re-established focusing as a linear phenomenon. In these examples, focusing is due to anti-diffusion due to discretization of convection and diffusion terms.

In 2015: Manoj Rajpoot led development of compact schemes for non-uniform grids. Paper by Aditi Sengupta and TKS appeared in JCP (2016) followed by sixth order scheme by Nidhi Sharma, Aditi Sengupta, Roshan Samuel, Manoj Rajpoot, TK Sengupta in Computers and Fluids (2017). This should boost research on IIM/ IBM. Also reported are properties of methods and filters using unstructured grid methods in this CAF paper.

We have reported accurate results for Rayleigh-Taylor instability by avoiding Boussinesq approximation and Stokes' hypothesis (incorporating bulk viscosity for Navier-Stokes equation). We have published work on non-equilibrium thermodynamic aspect of RTI in: Int. J. of Thermodynamics, Physics of Fluids, and in CPC proceedings.

• Other News:
We are revisiting vortex-induced instability using 3D V-Omega formulation. We have used vorticity-vector potential formulation for Navier-Stokes equation for 3D Taylor-Green vortex problem. Results have been published in Physics of Fluids by Dr. Nidhi Sharma and TKS.

Pramod is now Professor in Univ. of Pune; Yogesh leads a team at IIT Bhubaneswar; Dr. A Kameshwar Rao is at IIT Madras (Mech. Engg.); Prof. Manoj T. Nair is at IIST (Thiruvananthapuram); Prof. K. Venkatasubbaiah is in IIT Hyderabad. Other members of HPCL: Anurag Dipankar (Scientist in Singapore). Sreejith is a PhD candidate at CERFACS, Tolouse. Dr. Vijay Vedula, a faculty in Columbia Univ., New York. Shakti (UIUC, PhD) works for Cummins, Dr. Unnikrishnan at Florida SU, Ashwin V M (KTH, PhD) is doing post-doc in Stockholm and Shriramakrishnan (Postdoc in Switzerland after PhD, Univ. Texas). Dr. Kathikey Asthana is in NY, USA, (PhD, Stanford). Vishal Srivastava (PhD candidate, Univ. of Michigan). Vivek Joshi, Mohit Tekriwal and Sahil Bhola are now Graduate students in Univ. of Michigan.

Following works were presented in 2015: i) Indian Science Congress for an invited talk; ii) Keynote speech in Int. Conf. on Fluid Mechanics at Univ. of Gauhati; iii) JETC Conf. on Thermodynamics in Nancy, France; iv) Keynote speech and contributed paper in Turbulence & Interaction (TI-2015) at Corsica, France; v) Conf. on Computational Physics (CCP-2015) at IIT Gauhati and vi) an Invited talk in SAROD-2015 at VSSC.

    • IUTAM symposium on Advances in Computation, Modeling and Control of Transitional and Turbulent Flows held in Goa, India in December, 2014. The details about the proceedings from WSPC is at: http://spectral.iitk.ac.in/hpcl/IUTAM2014

    • Paper titled Precursor of transition to turbulence: Spatio-temporal wave front by Dr. Swagata Bhaumik and Tapan Sengupta in Phys. Rev. E explains by DNS the route to turbulence by harmonic wall excitation. Click for paper
    • "Diffusion in inhomogeneous flows: Unique equilibrium state in an internal flow," . A major work shows how small scales are created by diffusion for 2D/3D inhomogeneous flows, from Navier-Stokes equation without any assumptions. For 2D flows, this is the only mechanism. For inhomogeneous flows this is, thus, more general than any other existing concepts! See our new work on Taylor-Green vortex in Physics of Fluids (2018) and on Vortex-Induced Instability in Physics of Fluids (2018), PRE (2019).

    • The book : "Theoretical and Computational Aerodynamics" has been published by Wiley, UK. See the review in Aeronautical Journal of Royal Aeronautical Society, Feb. 2015 issue. Contains chapters on (i) computational aerodynamics, (ii) NLF and transitional flow related to aerodynamics, (iii) transonic aerodynamics and (iv) low Reynolds number unsteady aerodynamics.

    The book: "High Accuracy Computing Methods: Fluid Flows and Wave Phenomena" is published by Cambridge University Press (2013) with an Indian edition available. See:
http://www.cambridge.org/9781107023635

    • Swagata Bhaumik's PhD work on transition and turbulence is culmination of contributions by HPCL over the past two decades, starting with the work on Bromwich contour integral methods in early 90's.

    • A 40 parts lecture series on Foundations of Scientific Computing taught to IIT Kanpur undergraduate students (2009) is available as NPTEL course. Similar video course on Transition and Turbulence is also available. Ignore the transcription on screen - those were not done by us!

NPTEL Courses:
1. Foundations of Scientific Computing (2009)
http://nptel.ac.in/courses/101104013/
2. Instability and Transition of Fluid Flows (2010)
http://nptel.ac.in/courses/101104015/

    • The book: "Instabilities of Flows and Transition to Turbulence" published by CRC Press, Taylor & Francis Group, USA with details in:
http://www.crcpress.com/product/isbn/9781439879443

    • Prof. T. K. Sengupta has helped Tata McGraw-Hill for the Indian edition of Fundamentals of Aerodynamics by Prof. J. D. Anderson, augmented with SI Metrication and a chapter on Aerodynamic Research Activities in India written by him.

    • Recent trends in HPC at HPCL, IIT Kanpur, Sep 2009: Account of work done in HPCL, IIT Kanpur, on methods for DNS/ LES was displayed in the Workshop on "High Performance Computing in India" in conjunction with "Supercomputing 2009" (SC09), Nov. 14-20, 2009 (USA).

    • Issues related to DNS / LES were the central themes of the plenary talk given at 5th M.I.T. conference, Boston, June 2009

1. Three-time level methods like second order Adam-Bashforth schemes are incorrectly used for "DNS". Following papers show that numerical/ spurious mode removes large fraction of initial condition at higher frequencies. Details in HIGH ACCURACY COMPUTING METHOD (CUP, 2013) and the following papers:

a) A Comparative Study of Time Advancement Methods for Solving Navier-Stokes Equations

Dowload comparative study.. paper from springerlink

b) High Accuracy Schemes for DNS and Acoustics

Download the DNS and acoustics paper from springerlink

2. The von Neumann analysis for PDEs has been corrected, with the help of 1D convection equation, diffusion equation and convection-diffusion equation now. See the following papers:

a) Error Dynamics: Beyond von Neumann Analysis -- T.K. Sengupta, A. Dipankar and P. Sagaut, 226, 1211-1218 (2007)
Dowload Error dynamics: Beyond von Neumann analysis paper from Science Direct

b) Error dynamics of diffusion equation: Effects of numerical diffusion and dispersive diffusion -- T.K. Sengupta and A. Bhole, Journal of Computational Physics, vol. 266, pp 240-251 (2014)

c) Spectral analysis of finite difference schemes for convection diffusion equation-- V.K. Suman, Tapan K. Sengupta, C. J.Durga Prasad, K. Surya Mohan, D. Sanwalia, Computers and Fluids, vol. 150, pp 95-114 (2017)

Spectral.iitk.ac.in

Search

Information

User login

Site Counter

Announcements related to HPCL