Compressible Flow: Beginner CFD Training Package — Ep 09
Aerospike: Shock Wave
- Lesson
- 09
- Run Time
- 9m 20s
- Published
- Aug 10, 2026
- Category
- Compressible Flow
- Course Progress
- 0%
Description
This project simulates an aerospike using ANSYS Fluent. The goal is to model a nose cone fitted with an aerospike and to study how it reshapes the shock wave — pushing it away from the nose cone — and thereby reduces drag. Because the vehicle travels at supersonic speed, the flow is fully compressible, and the analysis centers on resolving the shock structure that forms ahead of the body — a defining feature of compressible flow.
A drag-reducing aerospike is a device used to lower the forebody pressure drag of blunt bodies at supersonic speeds. The aerospike creates a detached shock ahead of the body, and a zone of recirculating flow forms between the shock and the forebody. This recirculation zone acts like a more streamlined forebody profile, which reduces the aerodynamic drag.
The geometry was created in ANSYS Design Modeler, and meshing was performed in ANSYS Meshing using an unstructured grid with a total of 153,987 cells. The figure below shows an overview of the mesh.
Methodology
The simulation uses the k-omega SST turbulence model, with the flow set to Mach 2. At this speed the air must be treated as a compressible medium, so the solver captures the density variations and shock waves that govern the aerodynamics of the aerospike.
Conclusion
On completion of the solution, two-dimensional velocity contours and an animation were obtained. The results show that the aerospike produces a much thinner and weaker oblique shock, positioned well away from the cone. Because the pressure gradient of the primary shock wave now sits far from the body, the drag is reduced.
A small separation region also forms on the cone itself, and the reattachment of the separated flow together with the oblique shock occurs at some distance from the main body — which reduces the aerothermodynamic efficiency. Overall, the simulation illustrates a classic compressible-flow phenomenon: how modifying the shock structure ahead of a supersonic body can achieve meaningful drag reduction on a blunt forebody.