How do I use the moment plot in the post processor. I understand how the force plots work but I am not sure what exactly the moment plot is showing.
Hi @cyrus_costa, thanks for your post on the forum 
Just as the forces plots show the reaction forces on the structure, the moments plot show the reaction moments. These are two different phenomena which are crucial for structural analysis for example, since you need two conditions to be met for equilibrium:
\mathrm {\sum \mathbf{F} = \mathbf{0} } \tag{1}
\mathrm {\sum \mathbf{M} = \mathbf{0} } \tag{2}
The moment is vectorally defined by:
\textbf{M} = \textbf{r} \times \textbf{F} \tag{3}
Where \textbf{r} is the vector distance from the reference point for calculation of momentum to the point where the force is applied.
For more information please take a look:
Does that help?
Best,
Igor
I guess I am still a little confused. I use the forces feature to calculate the downforce on my car but I am unsure of how the moment plot helps me and how it can help me. What units is the moment plot in? I think knowing the units could give me a better understanding of what the data means. I also have not studied aerodynamics so there could be something I am missing.
Hi @cyrus_costa,
The units for the moment are of \mathrm{Lenght \times Force}. If in SI, it would be for example N.m
A colleague of mine also pointed out that, for CFD analysis, moment is relevant in the calculation of the potency of a turbine for example, as per in this tutorial:
In such a case, Potency is given by
\mathrm{P = T\omega}
Where \mathrm{T} stands for Torque.
Best,
Igor
1 Like