Identification of particular hydrodynamic parameters for a modular type 4 DOF underwater vehicle by means of CFD method

Nomenclature

A

reference surface area;

C_A

additional coriolis matrix;

C_d

drag coefficient;

C_L

lift coefficient;

C_MR

roll moment coefficient;

C_MY

yaw moment coefficient;

C_RB

rigid body coriolis matrix;

C_αε

k-ε turbulence model constant;

C_bε

k-ε turbulence model constant;

C_cε

k-ε turbulence model constant;

C_Y

lateral force coefficient;

d

momentum arm;

dt

time step;

ρDu/dt

deviation rates for a unit volume in the cartesian directions x,;

ρDυ/dt

deviation rates for a unit volume in the cartesian directions y,;

ρDw/dt

deviation rates for a unit volume in the cartesian directions z,;

D_Q

quadratic damping matrix;

D_L

linear damping matrix;

F

force;

F_D

drag force;

F_L

lifting force;

G_b

turbulence due to lifting forces;

G_k

turbulence kinetic energy generation;

k

turbulence kinetic energy;

K

roll momentum;

M_A

added mass matrix;

M_RB

rigid body mass matrix;

ε

turbulence propagation rate;

µ

dynamic viscosity;

ɳ

position and orientation vector;

N

yaw momentum;

P

electrical power;

ρ

fluid density;

Re

Reynolds number;

σ_k, σ_ε

turbulence Prandtl constants;

Τ

torque;

u

surge speed;

υ

towing speed or AUV speed;

v

sway speed;

w

heave speed; and

y⁺

dimensionless First layer thickness.

1. Introduction

Hydrodynamics deal with the motion and interaction of a solid body in a liquid. The hydrodynamic structure of an unmanned underwater vehicle (UUV) determines the vehicle’s performance and energy efficiency. Cylindrical or torpedo-shaped UUVs have advantages because of their energy efficiency and their simplicity for the analytical determination of hydrodynamic models. At present, underwater research, mostly performed in academic and industrial studies, is carried out for different purposes in civil and military applications, such as protection and investigation of natural and environmental resources, construction activities and coastal and country security. Sahoo et al. (2019) examined the localisation and navigation techniques used in existing autonomous underwater vehicles (AUVs). In this study, various control methods and optimised path planning methods for mapping, localisation and navigation that address sensorial technologies are discussed. The factors that make the studies in this field difficult include material wearing due to the effects of salt and pressure, the strong effects of wave movements in the sea and the extremely limited bandwidth of seawater...

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