In the third part of this blog, we will be explaining how to model water flow in a cylindrical underground tunnel. This flow is a result of the interaction between two water streams from circular channels. We will be using CFD modelling of open channel flow in Ansys Fluent.

## Open Channel Flow in Underground Circular Tunnels

Underground channels are used in water systems and other hydraulic applications. We can use CFD modelling of open channel flow in a circular channel for flow analysis in an underground tunnel. The intricate balance between water and air in these confined spaces presents a unique challenge that can be effectively addressed through the power of computational fluid dynamics (CFD) modelling. CFD modelling allows engineers to explore the complexities of open channel flow and gain a comprehensive understanding of its behaviour. By accurately representing the tunnel geometry and defining the fluid properties, engineers can simulate and visualize the flow characteristics with remarkable precision.

It is important to understand the differences between internal flow in pipes and open channel flow when it comes to CFD modelling. In the case of pipe flow, the fluid fills the pipe, whereas in open channel flow, the fluid only partially fills the channel, leaving a free surface between the air and water. In internal flow, pressure difference is the main driving force, while in open channel flow, gravity plays a significant role, especially due to the sloping nature of the channels. Furthermore, in internal flow, the maximum velocity occurs at the center of the pipe, while in open channel flow, it is at its highest just below the free surface.

## CFD Flow Analysis in Underground Tunnels

We have utilized the volume-of-fluid (VOF) method for CFD modelling to study the behaviour of fluids in a cylindrical tunnel. We have created a video tutorial that covers the process of setting the channel geometry, defining fluid properties, applying appropriate boundary conditions, and extracting the results. This tutorial will be helpful for those who want to learn the VOF method and simulate open channel flow in Ansys Fluent.

Modelling water flow in underground tunnels using open channel flow model in Ansys Fluent

## Summary

This blog explains how to use CFD modelling to analyze flow in underground cylindrical tunnels. Accurate representation of tunnel geometry and fluid properties is crucial for validation. By utilizing CFD modelling techniques, engineers can optimize design, improve efficiency, and ensure safety in underground infrastructure.

###### Tags:
CFD, Ansys, Fluent, Open Channel, Tunnel

February 13, 2024