Control Project
Resume:
Sonachalam Sekar
SE
Bothell, WA
Residence:
Mobile: (425)
Email: abqgx6@r.postjobfree.com
EDUCATION
Ph.D. from Department of
Applied Mathematics, Indian Institute of Science, Bangalore (1986)
Research Supervisor: Prof.
G. Nath
Thesis title: Boundary
Element Method Applied to Fluid Flow Problems
M. Sc University of
Madras (1979)
Mathematics. Passed with
Grade A
B. Sc University of
Madras (1977)
Mathematics, Physics and
Chemistry. Passed with First class
AWARDS
Recipient of Dr. Biren
Roy Trust award for the year 1991.
Was awarded by the
Aeronautical Society of India for Outstanding contribution in the field of
Aeronautics.
Recipient of DRDO
Technological award (1996)
For developing two new
numerical schemes for hypersonic flow computations in the field of
computational Fluid dynamics.
Recipient of DRDO
commendation award (1989)
Was awarded by Defense &
Research & Development Organization in recognition of the significant
contributions made to the Integrated Guided Missile Programme
Recipient pf Sir S
RadhaKrishnan award (1979)
Was awarded by Voorhees
College, Vellore, University of Madras for Outstanding ability in
Mathematics in M. Sc
WORKING EXPERIENCE
Started the carrier (1984) as
a Defense scientist-B, Computer Centre, DRDO and worked in the field of Kalmann filtering, Fluid dynamics, parallel programming
and embedded system till 1999 and rose to Director-1/Deputy head CFD division, DRDL.
Then (1999) joined in
PortalPlayer Pvt Ltd, Hyderabad and then Portalplayer Inc, USA(1999) to
lead the Audio core Technology Division.
Audio/Video
Seven year experience in
working and leading codec team as "tech lead" which including the
following areas.worked experiences in optimization and
implementation of MP3, WMA, AAC, ATRAC3(Sony),JPEG, OGG, MJPEG,
SBC and wav codecs in real
time system with dual ARm processorsdevelopment work in equalizer, bassboost, spatial
enhancement, automated gain control and other post processing effectsfirmware implementation of these codecs and it
functionalitiesguided an MS project in huffmann codingdesigning CRC algorithm for data checkfamiliarity with ECC, DRM algorithims
Software & Firmware
Lots of experiences in working with SOC (system on chip)
which is basically meant for audio and video products.. This SOC
is based on the twin ARM7TDMI and RTXC as OS.Good in writing the parallel and vector processor
algorithms for twin ARM processors and/or with Vector floating point
unit, VCP1 and VCP2Exposure to ARM assembly optimization for Audio
codec, ADS, MAT lab, visual slick edit, Multi-ICE toolsFamiliar with Linux, windows, Unix and other main
frame OSKnowledge in C, C++, FORTRAN, PostScript, UML Knowledge in codec like Mp3, AAc, Wma, JPEg, Mjpeg,
sony-AT3 and programming experience in hardware codec like AC-97 and
Wolfson codec Experience in designing Equalizer, Bassboost,
spacial enhancement, automated gain control and other post processing
technique.exposure to ECC, DRM and Rijndael algorithims.Heading and leading the Audio Core Technology team
and provided the solutions to one the world most popular product in the
Portable juke box market.
Computational experiences:
8 years of experience in the field of
Computational Fluid Dynamics(CFD), Aerodynamics, Parallel Programming in
MIMD, Trajectory Optimization, Grid Generator and Fluid Flow Analysis.
Designed and developed a flow analysis software called BHEEMA with new
algorithm.
PROJECT BHEEMA
Work carried out in the area of CFD (computational
Fluid dynamics) and in High Performance Computing.
(I) Development of industry standard code: BHEEMA
Under the guidance of Prof. SM Deshpande I have
developed an industry standard 3D Euler code called BHEEMA (Boltzmann
Hypersonic Euler equation solver for Missile Aerodynamics) which is based
on new method called Kinetic Flux Vector Splitting Method (KFVS). This is
a joint venture between DRDL (Defence Research & Development Lab.) and
IISc (Indian Institute of science). This is a first 3D KFVS code for
practical configurations and it was also possible to move from research
table to design mode in the shortest time.
(II) Basic principles of the KFVS method: To
construct a numerical upwind scheme for Euler equations is difficult
because it is vector nonlinear equations. We know that Euler equations of
motion are the moments of the Boltzmann equation whenever the velocity
distribution function is a Maxwellian. Hence by taking suitable moments to
splitted Boltzmann equation gives an upwind scheme for Euler equations.
This 'moment method strategy' turns out to be an extremely rich
methodology for developing robust upwind numerical schemes. Since
Boltzmann equation is scalar and linear it is easier to introduce
upwinding at the Boltzmann level. Then by taking suitable moments to
those equations we get mapped upwind Euler solver. Even the flow tangency
boundary condition on the body surface is also treated at the Boltzmann
level without any artificial cells.
(III) Some significant features of BHEEMA: The
upwind Euler code BHEEMA written in FORTRAN C is a 3-D time marching cell
centered finite volume method based on kinetic flux vector splitting. The
code operates on finite volume network which is constructed by generating
a 3-D grid around a configuration either by rotating a two dimensional
algebraic grid in the meridian plane in the case of a purely axisymmetric
regions or by using the stacked grid method in the case of regions with
lifting/control surfaces. The algebraic grid generator is based on a
distance function approach and is used for the regions up to starting of
lifting/control surfaces and the stacked grid method employed in the
regions with lifting/control surfaces and beyond. The elliptic grid
generators with control are employed in generating cross section plane.
Since the code development is a continuous process
the code was upgraded to the present form. Some of the features of the
upgraded code are:
- The initial first order scheme was upgraded to
higher order scheme both in time and space.
- The single block structure has been upgraded to
Multi block structure to take care of base flow
(Within Euler limit) and multi-body
configurations.
The code is optimized for CPU time and RAM by
introducing
- Modular approach
- Moving window algorithms
- Loop-over-surfaces
- Out-of-loop computations
- Global local time stepping option
- Other more popular flux formulae have also
been incorporated
(like VanLeer, Osher etc.) to have an inter
code comparison
- Limited Pre and post processor have been
included
- Generalized parallel version of the code
has been generated
using the domain decomposition for a mesh
architecture
message passing MIMD parallel computers
II) Validation and Verification
After the initial code developments, validations
have been done on standard shapes like cone, hemisphere etc. for
supersonic and hypersonic Mach numbers. The validations of code were
methodically carried out which are as follows:
- Checking the normal R-H relations for known
shapes
- Checking against cone/sphere tables
- Inter code comparisons for some range of Mach
numbers
- Wind tunnel comparison up to available Mach
numbers
- Final check with actual flight data
(IV) Use of code BHEEMA by other Scientist/
Research scholars
Integrated 3-D Time Marching Kinetic based Upwind Code
BHEEMA M Nagarathinam, PhD thesis, Department of Aeronautics, IIT (M),
Chennai (1987) (This PhD thesis brings out the salient features of
Integrated time marching kinetic based upwind code BHEEMA and it
applications to some of the missile configurations speed regime varying
from subsonic to hypersonic.)
Project by JATP/IISC, PS Kulkarni (1998)(Numerical
simulation of in viscid unsteady flow in a closed air-intake has been
carried out to capture the unsteady nature of the flow and its frequency.
The possible remedy has been found out to suppress/reduce the oscillation
frequency. The frequency obtained by the simulation corroborates well with
data obtained from actual flight.)
Parallelisation of Euler code for MIMD computer; Deepak, KS;
MS (Engg) Project (1999), Dept. of Aerospace, IISC, Bangalore. ( The
single block structured Euler code has been parallised to suit the PACE+32
of ANURAG computer and applied to Prithvi configuration for validation.)
Analysis of hypersonic flows with equilibrium chemistry; P
Theerthamalai, ME Project (1995), Dept. of Aerospace, IISC, Bangalore.
(The code BHEEMA has been upgraded with 5 species equilibrium chemistry
model to evaluate the pressure and temperature of the AGNI payload at
hypersonic flow regimes. The effect of varying gamma on the temperature
and pressure has been brought out up to Mach 15.)
Novel Schemes based on wave particle splitting for
compressible flows N Balakrishnan, Dept. of Aerospace, IISc. Part of PhD
thesis. ( The BHEEMA has been upgraded with seven types of fluxes
including a flux based On wave particle splitting method to evaluate the
efficiencies of the various numerical schemes.)
(V) Application of BHEEMA in Design Analysis
BHEEMA has been applied to a variety of
configurations starting from very low subsonic Mach numbers to hypersonic
Mach numbers. Some of the flow situations encountered while analyzing on
practical configurations are described below.
a) Re-entry configurations
The typical reentry vehicle consisting of hemisphere
-cone -cylinder -flare with control surfaces was analyzed with BHEEMA for
Mach number 4 to 14 up to $\alpha$ 2 degree. The required grid is about
200 thousand finite volume generated by algebraic method about axis
symmetric regions and by stacked grid method at in the on wing-body
regions. The predicted aerodynamic coefficients are compared with
experimental data up to Mach no. 8 beyond which the obtained results are
taken as it is to the mission. (There is no wind tunnel in the country for
Mach no greater than 8.)
The full configurations of the typical reentry
vehicle with 1st stage, 2nd stage and reentry configuration has been
analyzed for the estimations of aerodynamic coefficients at crucial Mach
numbers, which occurs during stage separations. It required more than 1
million finite volume to capture the effect of the reentry control on to
fin tip control surfaces. The effects of reentry control surfaces on the
control surfaces of the 2nd stage have been studied.
b) Launcher-plume studies
Estimation of pressure and temperature on a
flame deflector surface when a rocket plume impinges on it has been done
in the fast using 1-D or at best simple 2-D analysis. It is essential to
do full 3-D simulation of the flow encountered in plume-deflector problem.
The CFD code BHEEMA with necessary modifications has been applied to the
plume problem to predict the flow pattern. The code is parallelized on the
message passing, loosely coupled, distributed memory architecture parallel
machine PACE+32 Along with the rocket exhaust plume conditions, a cross
wind speed of 20 m/sec has been ntroduced as one of the flow conditions.
The complete pressure distribution and velocity/Mach contours have been
obtained. The numerical simulation
shows that BHEEMA can be used for design of mobile
launcher.
c) Inter-Stage Flows Analysis
In a multi stage aerospace vehicle, the 2nd stage is
ignited much before the 1st stage being separated to avoid the negative
acceleration of the vehicle. The flow analysis of the rocket-plume with
stage-1 has been obtained for the design of inter stage of the vehicle.
The optimal distance between the 2nd stage nozzle exit plane and the 1st
stage is the vital input to the design.
d) Application to Transonic Flow
The hemisphere-cylinder shape of a typical fore body
configuration is analyzed at transonic Mach numbers. The actual aim is to
find out the down wash effect at the base, so as to fix the low aspect
ratio control surfaces at the right place. Since subsonic and transonic
the propagation is so high it requires large finite volumes to capture the
flow. Also, to study the panel-to-panel interference one has to include
the region behind the base to computational regions, which further
complicate the solver to multi block and huge requirement of RAM and CPU
time. However, only forebody has been studied and further running of full
configuration with base is under progress.
e) Air intake - I
The isolated axis symmetric spike type supersonic
air intake configurations of typical air breathing vehicle were studied
for a typical Mach number (at the range of 2.18) at the super critical
conditions to revel the following.
- Start on/ non-start conditions of air intake
- Building of back Pressure
- Shock pattern
- Cowl wall pressure variations due to angles
of attack
- Shape of the cone (spike)
- Air intake distance (length)
f) Air intake - II
The studies have been carried out on isolated spike
type supersonic air intake with extended computational regions to find out
the flow properties at e super critical and sub-critical conditions. This
study is carried out mainly to find out pressure oscillations inside the
air intake tube if any and find the solutions to suppress the frequency.
g) Bulbous nose -very low subsonic
As the Mach number reduces the validity of the
discretisation of the Euler itself questionable. Up to what low Mach
number the code can predicts? The typical configuration of a 'bulbous
nose with backward facing steps' is studied to capture the effect of
high/low pressure bubble regions.
h) Coaxial mixing flows
This is a typical scramjet application. Two coaxial
supersonic flows with different initial Mach numbers and pressure were
allowed to mix freely to study the 'characteristic of the mixing of
flows'. Since the dissipation available in the KFVS scheme allowed the
flow to mix and the results were found to be a 'good engineering
approximation' when compared with experimental results.
(VI) Exposure to Computers and Software
I have gained vast experience in working on a variety
of both sequential and all most all parallel computers which is available
with in the country in the processes of development, parallelization and
implementation of BHEEMA.
COMPUTER LANGUAGES KNOWN
PARALLEL PROGRAMMING IN FORTRAN
Using PACE, FLO SOLVER and ANUPAM (BARC) Parallel Machines
FORTRAN 77 &90
BASIC
OpenGL
POSTSCRIPT
PASCAL
CMAP(assembly HONEYWELL BULL)
REDUCE (Analytical solver)
C and C++
PUBLICATIONS
28) S Sekar, "The Usage of PACE+ MIMD Computers for
Kinetic Scheme based Euler Solvers", Workshop on HPC using MIMD Computers,
CFD Center, Indian Institute of Technology, Madras, Feb24-26, 2000
27) S Sekar, K Anandhanarayanan, R Krishnamurthy and
SM Deshpande, "Numerical Simulation of Rocket Plume-Flame deflector
Interaction", Presented in 6th ISCFD-99, Bremen,Germany and accepted in
the Computational Fluid Dynamics Journal (1999).
26) S Sekar, "Development and Application of Code
BHEEMA using Sequential and Parallel Computers", Gas Turbine Research
Establishment (CEP), Bangalore, Jan10-21, 2000
25) S Sekar "High Performance Computing for Missile
Applications using MIMD Computers", CEP on High Performance Computing, ITR,
Chandipur 756025,India, 31st Jan-4th Feb 2000
24) S Sekar, M Nagarathinam, BS Sarma and SM
Deshpande, "Analysis of Inter stage Jet plume flow analysis", submitted to 1st Int. Conf. on
CFD, Kuyto, Japan (2000)
23) R Krishnamurthy, PK Sinha and S Sekar,
"Applications of CFD to Missile Configurations", Indian Aeronautical Jl., Aug 1999,
special issue on CFD.
22) PS Kulkarni, S Sekar, M Nagarathinam and SM
Deshpande, "Numerical Simulation of Pressure Oscillation using BHEEMA for
a generic intake", 3rd Asian computational Fluid Dynamics Conference,
Bangalore, India, Dec1998.
21) S Sekar, "Application of Euler Code BHEEMA to
flight vehicles using MIMD Computers", 3rd Asian Computational Fluid
Dynamics Conference, Bangalore, India, Dec1998.
20) S Sekar, "Parallel Computing -A User
Perspective", Advanced Topics in parallel Computing (CEP), ANURAG, Hyderabad, Jan22-26, 1998
19) S Sekar, K Anandhanarayanan and R Krishnamurthy,
"Computation of Flow around Generic Missile Body with strap-ons using code BHEEMA",
7th Asian Congress of Fluid Mechanics, IIT Madras, India, dec 1997.
19) S Sekar, PK Sinha and P Theerthamalai, "3-D
Upwind Euler Solvers for complex Flight vehicle configurations", DRDO, INDIA-DERA, UK
Joint Workshop on CFD, Bangalore, India, sep 1997.
18) S Sekar, " Parallelisation of Euler Codes ",
Invited seminar, SVR College of Enng. Hyderabad, 1997.
17) S Sekar, " Application of Code BHEEMA for Missile
development", Invited paper, CEP-CFD, DRDL, 1996, INDIA.
16) M Nagarathinam, R Krishnamurthy, S Sekar and SM
Deshpande, "A 3-D time marching Upwind Euler Code "BHEEMA" for aerodynamic
Design and Analysis for Complex Configurations" 14th AIAA Applied
Aerodynamic Conference, New Orleans, Louisiana, USA, June 1996.
15) S Sekar, Invited Lecture on " The complexity in
parallelisation of Euler code in MIMD computers", CEP, ANURAG, Hyderabad, INDIA
1996.
14) M Nagarathinam and S Sekar, "CFD applications to
Missile developments", invited lecture, Thyagaraj college of enng. Madurai, 1996.
13) SM Deshpande, S Sekar, M Nagarathinam
(1994),"Kinetic Surface transpiration with KFVS Euler code for Treating Control Surface
deflection", to be presented at 6th Asian Congress of Fluid Mechanics, Singapore,
May1995.
12) M Nagarathinam and S Sekar, "On the applications
of Code BHEEMA for Practical Configurations using High Performance parallel
Computers", 3rd Conference on Advanced computing ADCOMP'95, Bangalore,
India, Dec 1995.
11) S Sekar, M Nagarathinam, R Krishnamurthy and SM
Deshpande, "3D KFVS BHEEMA as Aerodynamic Design and Analysis Tools for
Complex Configurations", 14th Int. conf. num. methods in fluid dynamics,
Jul-1994, Bangalore, India.
10) M Nagarathinam, S Sekar, " Mighty BHEEMA - The
Euler Code", 3rd Conference in CFD and Astrophysical Applications,
Kodaikanal, India, Dec 1994.
9) S Deshpande, S Sekar, M Nagarathinam, R
Krishnamurthy, P Sinha, and P Kulkarni, ``3-Dimensional Upwind Euler Solver using Kinetic
Flux Vector Splitting Method
(KFVS). Lecture Notes in Physics, No. 414, pp105-109
Springer-verlag (1992).
8)S Sekar, M Nagarathinam, R krishnamurthy, SM
Deshpande, "3D KFVS Euler Code BHEEMA as Aerodynamics design and Analysis
Tool for Complex Configurations" 14th Int. Conf. on numerical fluid
dynamics, jul11-15, 1994, Bangalore.
7) S. Sekar and G Nath (1991) ''Boundary Element
Solution of the Navier Stokes Equations for the flow in a square cavity``. Acta
Technica CSAV, No 1, Page 123-135.
6) S. Sekar and G Nath (1990)'' The Boundary Element
Solution for Navier Stokes equations in a constricted channel`` Acta Technica
CSAV, No. 5, page 620-641.
5) S Sekar and G Nath (1991) '' Study of Molecular
diffusion in oscillating flow in a pipe using the Boundary Element Method''.
Numerical Heat Transfer, Part A, Vol 20, page 354-366.
4) R Krishnamurthy, M Nagarathinam, PK Sinha, S Sekar
(1992) ''Elliptic Grid Generator around atypical Wing\-Body Section``,
Presented at National Conference on Aeronautics, held at
Bangalore, India during Sept. 1992.
3) S. Sekar (1981) ''Molecular diffusion in
oscillating flow in a pipe by Boundary Element Method`` [Presented at ISTAM
Conference, Calcutta, 1981].
2) S Sekar, et al (1984)'' Computerized design for
tree seed orchard" Indian Jl.of Forestry, Vol. 7(3), 256. Practically
implemented by the Forest Departments at Bangalore, Chittor and Sandal Research Centre,
Bangalore.
1) S Sekar, 'BOUNDARY ELEMENT METHOD APPLIED TO
FLUID FLOW PROBLEMS' PhD Thesis at Department of Applied Mathematics,
Indian Institute of Science, Bangalore, India (1986)
SPORTSGood in Ping-Pong (Table tennis). Represented in
university team at Indian Institute of Science BangaloreUsed to be a long distance runner (Not now!)
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