Explosion

Explosion — ANSYS Fluent CFD Simulation

Description

This project presents a CFD simulation of a TNT explosion — a problem central to engineering safety, military applications, structural protection, and blast planning. An explosion is a very fast exothermic reaction that suddenly produces large volumes of hot gaseous products, spiking pressure and temperature and launching compression waves that travel outward through the surrounding air. In this project, you'll model the rapid decomposition of TNT — where 2 moles of TNT generate 22 moles of gaseous products — and watch the resulting spherical pressure wave propagate and dissipate across the domain. Within the Reacting Flow: Beginner CFD Training Package, this project applies reacting-flow modeling to a blast event, introducing the transient wave propagation that defines explosion physics.

Methodology

The domain is a half-sphere of 5 m radius with a central TNT charge (a 5 cm radius half-sphere), built in SpaceClaim using symmetry to reduce cost, and meshed with a large structured grid of roughly 2.67 million elements capable of resolving a traveling wave. Because the problem involves moving pressure waves, a transient solver is required. The Species Transport model is set up with a defined species mixture and a volume reaction, with finite-rate turbulence–chemistry interaction and the direct source chemistry solver. The Realizable k-ε turbulence model is applied with the energy equation activated. A critical modeling choice is defining the mixture density as an ideal gas, which is what allows the simulation to capture the wave travel through the domain.

Analysis

Post-processing produces temperature and pressure contours over time, along with an animation of the propagating compression wave, and quantifies the wave speed at roughly 420 m/s. From these results you can follow how the rapid exothermic reaction spikes the pressure and temperature at the charge and launches the spherical compression wave that travels outward and dissipates across the domain. Blast modeling protects buildings, vehicles, and people, and the reacting-flow + ideal-gas + transient workflow built here transfers directly to detonations, deflagrations, gas explosions, and pressure-vessel safety analysis across defense, oil and gas, and process industries. By the end of this project, you'll be able to set up a transient reacting-flow explosion simulation, configure the Species Transport model with a volume reaction and finite-rate chemistry, apply the ideal-gas density needed to capture wave propagation, and interpret the pressure and temperature fields of a blast wave.