The MUFFINS project aims to develop the next generation of pioneering technologies, computationally-efficient tools and recommended practice for the safe, reliable and real-life designs of subsea structural systems transporting multiphase flows. The key subsea challenges concerning the fluid-structure interaction (FSI) effects due to multiphase flow-induced vibrations (MFIV), in combination with external flow vortex-induced vibration (VIV), are being comprehensively addressed. The project outcomes will be of significant industrial importance and will strengthen the UK international competitiveness in the subsea designs of multiphase flows for global offshore oil and gas applications.


To achieve the above aim, the specific objectives of the MUFFINS project are to:

  1. Identify the occurrence, transition and key features of liquid-gas slug flows in long-span pipelines and risers;
  2. Formulate 3D vibration models for pipes transporting fluids and determine their free vibration characteristics;
  3. Establish new mathematical ‘closure’ relationships for multiphase flow momenta coupled with flexible pipe oscillations, and investigate multiphase flow interfacial mechanisms with detailed liquid-gas flow features;  
  4. Characterise MFIV phenomena and associated FSI effects for a wide range of realistic fluid-pipe parameters, and identify the contributing VIV effects on the pipe response subject to combined internal and external flows;
  5. Improve existing two-fluid force models by incorporating the MFIV-FSI features, by accounting for VIV effects and minimizing the unnecessarily high level of model conservatism, simplifications and uncertainties;
  6. Innovate computationally-efficient fluid force models and tools for MFIV-FSI, and provide recommended guidelines for safe, reliable and real-life pipe/riser designs subject to MFIV and combined MFIV-VIV;
  7. Validate and verify models, numerical methodologies and prediction results with realistic experimental tests.


In achieving our objectives, several key questions currently faced by industry will be ultimately addressed.

  • What are the main hydrodynamic and geometric mechanisms causing slug MFIV in long flexible pipes?
  • What are the critical operational parameters generating unacceptable MFIV effects that must be addressed?
  • How can computational resources for solving coupled equations with multiple flow-structure unknowns be reduced, and how can such methodologies be creatively developed for ready use by industrial designers?
  • How can simple, predictive models that capture the observed MFIV-FSI phenomena and MFIV-VIV interactions be derived and applied to a range of practical cases without excessive calibration and costly experiments?
  • What are the safe, reliable, real-life pipe/riser designs with low-cost tools and sound recommendations acceptable to industry, globally, and how will these tools be integrated within existing industrial software?