# 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 (C_{p})

• Total pressure ratio (P_{t}/P_{t0})

• 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

• Maskell

• 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.