What mean by "from mass constraint" in plasma model
 

Hi all,

I noticed under plasma model, for the settings of each species it has the tick option of 'from mass constraint' may I know what is this means? The screenshot is shown in the attachment Attachment 97329

It's mean simply calculated by X(N)= 1-X(1)-X(2)-X(3)-...-X(N-1). X(1) to X(N-1) are masse fraction of other species.

I noticed, that by setting different species to mass constraint can result as converging error. So far what I know is to set the largest species to mass constraint is the correct way of doing it.

You should put only one specie to mass constraint

But is the one species must be the largets one? That is what I am trying to ask.