Experimental investigation on loads of nets with different types under current

Area of Science:

• Fluid dynamics
• Marine engineering
• Aquaculture engineering

Background:

• Net drag is a primary hydrodynamic load on marine cages, critical for structural integrity and operational safety.
• Limited research exists on how factors like material, mesh type, solidity, and angle of attack influence net hydrodynamic loads.

Purpose of the Study:

• To investigate the drag forces on nets using flume tests.
• To establish relationships between the drag coefficient and net properties (material, solidity ratio, mesh shape) and flow conditions (velocity, direction).

Main Methods:

• Conducted flume tests on six different net types.
• Measured drag forces under varying current velocities and directions.
• Calculated drag coefficients and analyzed their relationship with current velocity and Reynolds number.

Main Results:

• Net drag and drag coefficients are influenced by current velocity, windward area, mesh shape, net solidity ratio, and material properties.
• Obtained curves illustrating the relationship between drag coefficient and current velocity or Reynolds number for different nets.
• Compared and analyzed drag coefficients from tests with prediction models, clarifying model applicability.

Conclusions:

• Net drag is a complex phenomenon affected by multiple parameters beyond simple flow velocity.
• The findings provide essential data for accurate drag calculations in net cage engineering.
• Understanding these relationships enhances the design and safety of marine aquaculture structures.