Many offshore structures contain cylindrical elements, such as cladding platforms, jackets, tension-leg platforms and marine pipelines.However, exposure to current and waves can cause oil leakage. Conducts at intermediate water depths are subject to currents plus waves causing large variations in velocities and hence the Reynolds number (Re = UcD / υ, where Uc is the free flow velocity, D is the diameter of the cylinder and υ is the kinematic viscosity of the fluid) most often appears in the range from 10 ^ 3 to 10 ^ 7. It is therefore important to understand the flow around the circular cylinder in the effective Re range. In recent years there is a strong use of computational fluid dynamics (CFD) which is a branch of fluid mechanics that uses numerical analysis and data structures to solve and analyze problems involving fluid flow and also interaction between waves and structures. The main use of CFD is to solve the Navier-Stokes equations and their equations. There are therefore several methods to solve the Navier-Stokes equations, and since they are generally high-cost computational operations, more sophisticated model-based approaches have been developed: - Direct numerical simulation - Reynolds Averaged Navier-Stokes (RANS) - Large Eddy Simulation (LES) This article deals with the use of CFD to determine the flow field concerning the complex interaction of a cylindrical structure with a fluid using the approach based on Reynolds Averaged Navier-Stokes (RANS).

### NUMERICAL SIMULATION OF VELOCITY AND PRESSURE FIELD AROUND A CYLINDER AT MODERATE REYNOLDS NUMBER

#### Abstract

Many offshore structures contain cylindrical elements, such as cladding platforms, jackets, tension-leg platforms and marine pipelines.However, exposure to current and waves can cause oil leakage. Conducts at intermediate water depths are subject to currents plus waves causing large variations in velocities and hence the Reynolds number (Re = UcD / υ, where Uc is the free flow velocity, D is the diameter of the cylinder and υ is the kinematic viscosity of the fluid) most often appears in the range from 10 ^ 3 to 10 ^ 7. It is therefore important to understand the flow around the circular cylinder in the effective Re range. In recent years there is a strong use of computational fluid dynamics (CFD) which is a branch of fluid mechanics that uses numerical analysis and data structures to solve and analyze problems involving fluid flow and also interaction between waves and structures. The main use of CFD is to solve the Navier-Stokes equations and their equations. There are therefore several methods to solve the Navier-Stokes equations, and since they are generally high-cost computational operations, more sophisticated model-based approaches have been developed: - Direct numerical simulation - Reynolds Averaged Navier-Stokes (RANS) - Large Eddy Simulation (LES) This article deals with the use of CFD to determine the flow field concerning the complex interaction of a cylindrical structure with a fluid using the approach based on Reynolds Averaged Navier-Stokes (RANS).
##### Scheda breve Scheda completa Scheda completa (DC)
2019
Offshore structures; CFD; RANS; Velocity field; Pressure field; Numerical methods
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: `https://hdl.handle.net/20.500.12318/702`
• ND
• 0
• ND