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# Capabilities

Since Epsilon was conceived as an aerodynamic analysis tool, it includes the classical aerodynamic parameters used for performance assessment (like total pressure loss). On the top of that, the main four aerodynamic analysis methods are provided: near-field, far-field, Lamb vector and Exergy.

### Classical aerodynamic analysis:

Some of the variables provided by Epsilon are the following (among many other variables):

• Pressure coefficient (Cp)
• Total pressure ratio (Pt/Pt0)
• Vorticity
• Vortex detection (Q criterion, Lambda 2)
• Shock wave detection

Classical aerodynamic analysis
Shockwave and vortex detection, pressure coefficient at the wing surface and total pressure ratio at wake region

### Near-field method:

Epsilon calculates the classical near-field lift and drag forces (related to the pressure and friction forces acting upon the body surface). Moreover, spanwise lift and drag distributions by the near-field method can be visualized.

Near-field method
Spanwise lift and drag distribution (body surface integral)

### Far-field methods:

This is an alternative method to calculate lift and drag from wake data (CFD or experimental data). Its major asset is the drag breakdown (i.e., a decomposition of the total drag into profile drag, wave drag, viscous drag and induced drag). Several far-field formulations have been included in Epsilon:

• Momentum conservation
• Betz
• Jones
• Oswatitsch
• Van Der Vooren
• Giles
• Kusunose
• Meheut
• Onorato

A powerful flow analysis can be made by displaying the spanwise lift and drag distribuions:

Far-field analysis
Profile drag density at the wake plane. Lift (white), profile drag (cyan) and induced drag (magenta) distributions from wake data integral.

### Lamb-vector method:

This is a vorticity-based approach to calculate lift and drag forces acting upon a body. it can be considered as an extension of the well-known Kutta-Joukowski theorem (where lift is given by the product of the circulation and the velocity). Several formulations are included:

• Wu
• Mele

Lamb vector analysis
Spanwise lift distribution by integrating the local lift force (Lamb vector) in the boundary layer volume

### Exergy method:

This is a powerful aerodynamic analysis method based on simple Thermodynamic concepts: exergy and anergy. It allows calculating the drag acting upon a body as well as its drag breakdown. However, its major asset is the capability of pinpointing the room for improvement: energy waste in a given aerodynamic design is quantified and, most importantly, it provides an intuitive approach to recover this energy (i.e., drag reduction possibilities). Several formulations are included:

• Arntz
• Aguirre

Vortex exergy
Induced drag determination based on wake data (Aguirre method)

### What else?

Epsilon is a flexible platform: it allows the user to implement new equations or variables by simply modifying a Python code.

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