Dynamics of Floating Structures

Dr Subrata K Chakrabarti from Offshore Structure Analysis Inc, USA visited WIT to present a short course entitled Dynamics of Floating Structures.

The course had two main objectives:

1. To provide a basic understanding of wave hydrodynamics and wave structure interaction with particular emphasis to floating structure dynamics.

2. To gain experience with design analysis, computation, software, model testing and interpretation of results.

Each day a lecture was presented on a theoretical topic identified in the course outline. Subsequently, a discussion was made with relevant design calculation and use of wave tank data. Applicability in design and limitations of the formulas were discussed and demonstrated with the help of design charts.

Over a period of three days lectures were presented on the following topics:

  • Basic hydrodynamics
  • Airy theory
  • Stokes higher order theory
  • Stream function theory
  • Applicability of wave theories
  • Correlation of wave tank data
  • Exercise Problems
  • Morison equation
  • Inertia & draf coefficients
  • Vortex phenomena & lift forces
  • Diffraction theory
  • Free surface effect
  • Regions of applicability of formulas
  • Added Mass and Damping
  • Single degree of freedom
  • Six degrees of freedom
  • Moored system dynamics
  • Example FPSO Problem
  • Motion Instability Issues
  • Basics of wave energy spectrum
  • Common wave spectrum models
  • Random time history simulation
  • Statistical properties of waves
  • Short term response
  • Long term response
  • Exercise Problems
  • Modelling laws
  • Froude & Cauchy model
  • Available wave tank facilities
  • Simulation of environment
  • Instrumentation & model tests
  • Planning deepwater testing
  • Steady drift force
  • Slowly oscillating drift
  • Example Semi Problem
  • High frequency response
  • Low and high frequency damping
  • Practical example

Dr Subrata K Chakrabarti is the president of Offshore Structure Analysis Inc and the past Director of Marine Research Division of Chicago Bridge & Iron Company. He has over 30 years’ experience in offshore structure design and analysis, and has been involved in the development of many offshore production structures. He has published over 150 technical papers and has written four textbooks.