SHIPFLOW 7.0 released!

SHIPFLOW 7.0

We are happy to announce that the new major release of SHIPFLOW, version 7.0, is now available for download. We have added many new features and improvements that we think you will find very useful.

MOTIONS 7, the seakeeping module has been reworked significantly to increase accuracy, speed, flexibility and robustness. The main features of the software include:

regular and irregular waves
long and short crested waves
added resistance due to incoming waves
head and oblique waves
simulations with forward motions, stationary or free floating bodies
acceleration, velocity and translations of arbitrary points on the body
time series and Response Amplitude Operators
mooring lines, fenders, spring attachments (e.g. to carriage)
external force model interface ( Flettner rotors, wing sails, fins )
arbitrary geometries and multiple bodies
ship to ship/other floating or fixed bodies relative motions
times for good quality calculations: about 2-4h on an average desktop computer

MOTIONS 7 can be applied to: ships, yachts, boats, mono- and multi-hulls, semi-submersibles, floating platforms, floating wind mills and many more. See also a short presentation.

SHIPFLOW 7 also brings new RANS grid settings to improve accuracy of results for high block coefficient ships. The default hull roughness model and AHR/ks factor were set to give the most accurate results of full scale delivered power for ships in real conditions.

The customizable automatic post-processing has also been upgraded to utilize Paraview 5.10 and Python 3.9.

Validation of full-scale delivered power CFD simulations

A new paper published in Ocean Engineering Journal:

Michal Orych, Sofia Werner, Lars Larsson, 2021. Validation of full-scale delivered power CFD simulations. Volume 238, 15 October 2021, 109654

https://www.sciencedirect.com/science/article/pii/S0029801821010301

Abstract:

Verification and Validation of CFD simulations of delivered power at full-scale are carried out for a single screw cargo vessel. Numerical simulations are performed with a steady-state RANS method coupled with a body force propeller model based on a lifting line theory. There are no significant differences in the uncertainty levels between model and full-scale computations. The finest grid exhibits the numerical uncertainty of 1.40% at full-scale. Computed results are compared with sea trial data for three sister ships. Special attention is paid to the effect of roughness on the hull and propeller. The comparison error for the delivered power is about 1% which is significantly lower than the experimental uncertainty.

Keywords:

Delivered power; Full-scale; Hull roughness; Self-propulsion; Uncertainty; Validation; Verification; CFD

Improved methods for design of ships

"Improved digital tools for the hydrodynamic design of energy efficient ships – validation, demonstration and introduction to the maritime industry"

FLOWTECH has just successfully finished a project executed with support from the Swedish Energy Agency (Energimyndigheten). The results of the work include the following:

Verification and Validation of CFD simulations of delivered power at full-scale were carried out for ships for which high-quality sea-trial data was collected. Special attention was paid to the effect of roughness on the hull and propeller to improve the accuracy of the simulations. The comparison error for the delivered power was about 1% which shows that the simulations at full scale can very accurately predict power demands of new ships as well as ships in service.

The study performed within this project showed that the numerical optimization of ship hulls at full-scale could yield higher gains in power savings. The presented optimization process included the propeller-hull interactions, and a clear advantage of self-propulsion-based optimization was observed.

An efficient and accurate numerical procedure to estimate the decrease of ship speed in wind and waves was developed. It was used to calculate the weather factor of the attained energy efficiency design index for new ships, EEDI, for a tanker. The predictions were compared to the model test results and a database of similar ships. The comparison error was 1% for the resistance and the predicted weather factor was in line with the database values.

Materials with examples and analyses of the project results illustrating the new possibilities for developing energy-efficient hull shapes were prepared. Several papers for scientific journals were written and the resulst will be presented in the upcoming conferences and workshop on numerical ship hydrodynamics. The results will also be shared with the shipyards and design offices through the company network.