1. Department of Mathematical and Computational Sciences, National Institute of Technology Karnataka, Mangalore 575 025, India e-mail:
2. Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India e-mail:
3. TIFR Centre for Interdisciplinary Sciences, Hyderabad 500 075, India e-mail:
4. Engineering Mechanics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India e-mail: