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Announcements related to HPCL

We are going to remove the confusion surrounding the use of Adams-Bashforth method, once for all. The question regarding the role of spurious numerical mode which appears in all three-time level methods has been discussed in the following paper: AMC.pdf
Following audio-slide is for those fellow-scientists who wants to see the catastrophic breakdown of solution by the spurious mode. Here third order upwind scheme is used with Adams-Bashforth method. Rest is self-explanatory: AMC Audio slide viewer

Certificate of outstanding contribution in reviewing: Journal of computational physics, awarded July, 2015 to Prof. Tapan K. Sengupta. Certificate of Outstanding Reviewer JCP.pdf

1) Pramodkumar Bagade defended his PhD thesis successfully at IIT Kanpur; 2) Kartikey Asthana has defended his PhD thesis at Stanford University; 3) Jyoti Sangwan defended her M. Tech. thesis on compressibility effects on dynamic stall; 4) Atchyut defended his M. Tech. thesis on reduced order models and 5) Zulqarnain Akbar Shabab defended his M. Tech. thesis on transition by polychromatic excitation. He also investigated the start-up process of excitation on STWF.

Prof. Sengupta was on sabbatical leave during 2015-2016. He has spent three months in Bordeaux during winter; the following summer in Univ. of Cambridge, UK as a Visiting Fellow of Murray-Edwards College and Univ. Engg. Dept, working with Prof. Paul Tucker and his team. Subsequently, he visited Univ. of Bordeaux, as the visiting IDEX Professor in I2M Laboratory, working with Prof. Mejdi Azaiez and others during September and October, 2016.

MHRD sponsored Global Initiative on Academic Network (GIAN) program was held in IIT Bhubaneswar conducted by Profs. Yogesh Bhumkar and Satyanarayana during May 23- June 03, 2016. The speakers were Prof. D. V. Gaitonde (OSU, USA) and Prof. Tapan Sengupta (HPCL, IIT Kanpur).
Title of the course: Computational Acoustics: Engineering and scientific approaches.

Graduating students' farewell at HPCL in 2015. Photo

Book review of Theoretical and Computational Aerodynamics (John Wiley, UK) appeared in Aeronautical Journal of Royal Aeronautical Society. Writing this book was possible with help from all at HPCL.

Transition to turbulence-- the physical mechanism explained in:
Precursor of Transition to Turbulence: spatiotemporal wave front
by: Swagata Bhaumik and Tapan K Sengupta; In: Physical Review E.
PREVIEW LINK: http://spectral.iitk.ac.in/hpcl/LH13761E_25April2014.pdf
Journal link: http://journals.aps.org/pre/accepted/b307fY87Ub91fc3bd7776bb1d6fd45e9cb1...
Recent developments announced in the IUTAM SYMPOSIUM URL: http://spectral.iitk.ac.in/hpcl/IUTAM2014


Third International Conference on Meta Computing 2012, held in Bhubaneswar. Conference Co-Chair: Prof. Tapan K Sengupta Best papers: Drs. V. Mudkavi/ K. Venkatesh (NAL Bangalore) and Pramod Bagade/ B. Satish (IIT Kanpur)


DNS of Transition and Turbulence in Physical Review Letters - see link (1) below.
Also the paper: "Direct numerical simulation of two-dimensional wall-bounded turbulent flows
from receptivity stage" February 2012, Physical Review E (Vol.85, No.2):
URL: http://link.aps.org/doi/10.1103/PhysRevE.85.026308
Related links :
(1) http://prl.aps.org/abstract/PRL/v107/i15/e154501
(2) http://prl.aps.org/abstract/PRL/v96/i22/e224504
(3) http://www.sciencedirect.com/science/article/pii/S0021999107002537

News

    TKS was on sabbatical (Dec. 2015 to Dec. 2016) visiting 1) Univ. of Bordeaux, France and 2) Univ. of Cambridge, UK. He has presented various works done at HPCL at many European universities. Works on transition, high accuracy computing method and reduced order models have been presented.

Summer visitors at HPCL in 2015: Dr. Manoj Rajpoot and Prayash Panda studied compact schemes in non-uniform grids. Paper by Aditi Sengupta and TKS on this topic has appeared in JCP. Further work on this is in processing, to provide higher order scheme, numerical properties and filters for random grid spacing - all towards analysis of unstructured grid methods by GSA.

We are revisiting Adams-Bashforth method, as there are still so much ignorance about it globally! Some of it is very amazing!!

We have taken up the challenge in providing more accurate results for Rayleigh-Taylor instability. In the process, we have avoided taking Boussinesq approximation. More importantly, we have avoided making use of Stokes' hypothesis, by incorporating bulk viscosity for Navier-Stokes equation, another first from HPCL. We have published work on non-equilibrium thermodynamical aspect of RTI and removed Stokes hypothesis in our Physics of Fluids paper.

We welcome back Dr. Swagata Bhaumik in India, after his stay in OSU with Prof. Gaitonde. We also welcome Biswajit and Emayvarman as two PhD candidates joining HPCL. Prasanna, Deepak, Netrapal and Shamini have joined our group for M. Tech. programme. G.R. Krishna Chand Avatar from Punjab Engineering College is our youngest member of HPCL staying here for his internship. He is looking at multiple Hopf Bifurcation again.

Other News:
Jyoti has joined Eton; Atchyut is in Bangalore; Akhil is with Rolls Royce; Ijlal is placed with Airbus. Nilesh is teaching in Pune/ Mumbai. Prasoon and Soumyo are in Georgia Tech doing PhD. Dynamic stall work of Prasoon is not a new activity in HPCL, but is very accurate now. This follows the work of Sreejith and Ashish on developing transonic flow code, which is also modified for Rayleigh-Taylor instability (RTI). Aditi is in Univ. of Cambridge. Nidhi and Roshan have developed a 3D compressible ILES code for 3D RTI. Vikram Singh (2009 BT-MT) has joined Technion for his PhD. Pushpendra Sharma (PhD student) is working on DNS/LES of 3D internal flows. He will work on reduced order model - a collaboration with Univ. of Bordeaux. He has started work on channel flow transition.

Dr. A Kameshwar Rao is at IIT Madras (Mech. Engg.); Prof. Manoj T. Nair is at IIST in Thiruvananthapuram; Dr. Sudipta De is at CMERI Durgapur and Prof. Venkatasubbaiah is in IIT Hyderabad. Other senior members of HPCL: Sarthok Sircar is a faculty at IIIT Delhi, after his stay at Univ. of Adellaide; Anurag Dipankar is in Singapore. Rajarshi is doing his PhD at UPMC, Paris. Vijay is doing his post-doc in Stanford. Shakti is in UIUC doing PhD, Unni has finished PhD at OSU, Columbus, Ohio, Ashwin VM is at KTH and Shriramakrishnan is in Univ. of Texas. Abir and Himansu are with Eaton; Pallavi, Lakshmanan and Sreejith are with GE.

Following works were presented at conferences/ workshops 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 was held in Goa, India during 15-18 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 wall excitation. Click for paper

    "Diffusion in inhomogeneous flows: Unique equilibrium state in an internal flow," Tapan K. Sengupta, Himanshu Singh, Swagata Bhaumik, Rajarshi Roy Chowdhury. A major work shows how small scales are created by diffusion for 2D/3D inhomogeneous flows, from Navier-Stokes equation without any assumptions. This mechanism is much stronger than vortex stretching, for 3D flows. For 2D flows vortex stretching is absent. For inhomogeneous flows, this is, thus, more general than any other competing ideas!

    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. A companion volume has appeared with problems and lots of animations explaining certain aspects of Aerodynamics. Check Wiley site for further details.

    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 and heat equation. See the following papers from J. Computational Physics:

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)