Moment (EMP)

This report is available only for Eulerian Multiphase (EMP) domains. The Moment (EMP) report is similar to the Moment report. It reports the moment exerted on each part due to interaction with the EMP phases.

The moment report is defined as:

Figure 1. EQUATION_DISPLAY

M = \sum_{f}^{} [r_{f} \times (f_{f}^{p r e s s u r e} + f_{f}^{s h e a r})] \cdot a

(451)

where $f_{f}^{p r e s s u r e}$ and $f_{f}^{s h e a r}$ are the pressure and shear force vectors, $a$ is a vector defining the axis through point $x_{0}$ about which the moment is taken, and $r_{f}$ is the position of face $f$ relative to $x_{0}$ .

The Eulerian Multiphase (EMP) flow model assumes that the pressure is the same in all phases, therefore the pressure force vector on surface face is computed as:

Figure 2. EQUATION_DISPLAY

f_{f}^{p r e s s u r e} = (p_{f} - p_{r e f}) a_{f}

(452)

where

p_{f}

is the face static pressure,

a_{f}

is the face area vector, and

p_{r e f}

is the reference pressure.

Note

The report reference pressure

p_{r e f}

is defined relative to the simulation reference pressure. This definition means that a

p_{r e f}

of 0 Pa does not indicate absolute zero pressure, but is rather the value of the simulation reference pressure. Further, when the surface on which the force is computed is a closed surface, the choice of

p_{r e f}

affects only the overall accuracy of the result: therefore set it to a value that is close to the average pressure on the surface. For an unclosed surface,

p_{r e f}

is effectively the pressure that is applied on the back-side of the surface, and therefore directly affects the result.

The Eulerian Multiphase (EMP) flow model solves the momentum conservation equations for each phase. The shear force is a function of the physical properties and velocity, therefore for EMP simulations the shear force exerted on the surface is the sum of the contributions from each phase, defined as:

Figure 3. EQUATION_DISPLAY

f_{f}^{s h e a r} = \sum_{i}^{} τ_{i, f} \cdot a_{f}

(453)

where $τ_{i, f}$ is the wall shear stress from phase $i$ at boundary face $f$ .

Moment (EMP) Report Properties

In addition to constants, you can enter field function syntax directly.


Units	Units that are used for specifying the quantity.
Coordinate System	A list of coordinate systems in the simulation for use by this report.
Axis	A Cartesian vector specifying the axis $a$ of aEqn. (451)bout which the moment is computed.
Force Option	The forces (shear and pressure) that are considered in the computation of the moment.
	Shear	Only the force due to shear, $f_{f}^{s h e a r}$ in Eqn. (451), is considered.
	Pressure	Only the force due to pressure, $f_{f}^{p r e s s u r e}$ in Eqn. (451), is considered.
	Pressure + Shear	Both pressure and shear forces, $f_{f}^{p r e s s u r e}$ and $f_{f}^{s h e a r}$ in Eqn. (451) are considered.
Reference Pressure	The reference pressure for the computation of Eqn. (452).
Axis Origin	A Cartesian position vector specifying the point $x_{0}$ on the axis $a$ about which the moment is taken.
Parts	A list of parts that is used as the source for this report. Opens the in-place part selector for editing. The (property customizer) button activates a modeless version of the selector dialog (it lets you interact with other portions of the workspace).

Moment (EMP) Report Expert Properties


Number of Bands	A text entry for the number of bands into which to divide the model.
Representation	Selects a representation. Additional selections appear as representations that are added to the simulation.
Smooth Values	When this property is activated, the report is calculated using node (interpolated) values of the chosen quantity rather than cell values.