# Hydrodynamic Performance Enhancement of Torpedo-Shaped Underwater Gliders Using Numerical Techniques

## TL;DR

This paper studies how to improve the hydrodynamic performance of torpedo-shaped underwater gliders using numerical simulations and geometry optimization.

## Contribution

The study introduces a novel approach to optimizing nose geometry and turbulent models for drag reduction in underwater gliders.

## Key findings

- Using the Spalart-Allmara model reduced validation error to 1.28%.
- Decreasing velocity reduced drag force by 37.3%.
- Nose length optimization reduced drag by up to 3.37%.

## Abstract

Underwater gliders are widely used in marine applications for monitoring purposes. These gliders must withstand hydrodynamic forces and maintain its body stability. The underwater environments are highly unpredictable, and small changes in the environment can lead to significant instability in underwater vehicles.

This study uses different numerical techniques to investigate the hydrodynamic characteristics of a torpedo-shaped glider. A symmetric torpedo-shaped glider model was created and analyzed using a licensed version of ANSYS 20.1 Fluent tool. The behavior of the torpedo glider under various flow conditions was examined such as variation of grid test, change of turbulent models, the variation in the inflow boundary conditions involves varying the velocity from 10.16 m/s to 15.16 m/s in 1m/s increment and from 10.16 m/s to 7.66 m/s in 0.5 m/s, also six different models were analyzed.

Research was also attempted with different turbulent models and the Spalart-Allmara model was producing least validation error of 1.28 % with a primary focus on nose optimization. By varying the nose length, the study aimed to identify the best-suited nose geometry to minimize drag force. The nose lengths were varied to 0.205 m and 0.19m, resulting in validation errors of 2.81% and 1.16%, respectively, the results are clearly explained in the sub sequent sections of this article.

In conclusion, this study has evaluated various modifications and their impact on drag force reduction. The application of Spallart-Allmara model resulted in an improvement of 1.28%. Decrease in velocity lead to a significant reduction in the drag force, with an improvement of 37.3%. The nose optimization also contributed to drag force; a nose length of 0.205m yielded a 3.37% improvement. While a 0.19m nose length resulted in a 1.67% reduction. This study helps researchers in hydrodynamics by optimizing geometry for drag reduction.