The basis of Vivana

The hydrodynamic model in Vivana is based on empirical coefficients, while the structural model applies a non-linear 3-dimensional finite element formulation.

The program is able to work with an arbitrary distribution of tension, mass, stiffness, buoyancy and diameter.

Response frequencies are identified while considering a frequency dependent hydrodynamic mass along the structure.

Response amplitudes are calculated at the discrete frequencies by the frequency response method

The excitation force model includes a lift coefficient that is a function of the response amplitude and the response frequency.

Damping outside the excitation zone is introduced by high and low velocity damping terms.

What will Vivana software provide for the user

• Free variation of all parameters (diameter, Strouhal number, coefficients etc.) along the riser
• Frequency dependent hydrodynamic mass matrix
• Identification of dominating and possible response frequencies
• Identification of excitation and damping zones for all response frequencies
• Calculation of response amplitude
• Calculation of fatigue damage
• Calculation of drag amplification