# Rotating Cylinder Force (IL)

Centripetal pressure gradient for components in an isothermal liquid system

*Since R2020a*

**Libraries:**

Simscape /
Fluids /
Isothermal Liquid /
Actuators /
Auxiliary Components

## Description

The Rotating Cylinder Force (IL) block models the axial force due to a centripetal
pressure gradient in a rotating shaft about its symmetry axis, which is found in
applications such as friction clutches, square-jaw positive clutches, dog clutches, and
brakes. Connect this block in parallel to a Single-Acting Actuator (IL) or a Translational Mechanical Converter (IL) block to model a
rotating actuator. The fluid density is recorded at the isothermal liquid port
**X**. The angular velocity is received as a physical signal at
port **W**. Port **R** is associated with the piston
velocity, relative to the case at port **C**.

The angular velocity of the shaft is assumed to be constant or nearly-constant, and therefore the fluid is considered to be in rigid-body rotation.

The centripetal force is due solely to the fluid angular momentum induced by shaft rotation. Removing the contribution of the static pressure in the fluid channel, the contribution of the rotation of the shaft to the axial force is:

$${F}_{rotational}=\frac{\rho \pi {W}^{2}}{4}\left({r}_{o}^{4}-{r}_{i}^{4}-2{r}_{p}^{2}\left({r}_{o}^{2}-{r}_{i}^{2}\right)\right),$$

where:

*ρ*is the fluid density at port**X**.*W*is the angular velocity of the rotating pipe, received as a physical signal at port**W**.*r*_{o}is the**Piston outer radius**.*r*_{i}is the**Piston inner radius**.*r*_{p}is the**Fluid entry radius**.

## Ports

### Conserving

### Input

## Parameters

## Extended Capabilities

## Version History

**Introduced in R2020a**