If I understand your question, you're stuck trying to figure out Wall Temperature. But I don't know what Wall Temperature is. Is that a term that is well-defined in some knowledge domain? Is it the average temperature at the boundary? The max? Min?

On the other hand you use the term "dimensionless temperature". What's that? I would have thought you just want something like QuantityMagnitude, but that doesn't seem to fit with the way you use the term.

Can you rephrase your question so that we know what you're trying to achieve without us having to understand the knowledge area you're working in? Can you make this a question about Mathematica specifically?

Thank you, I will try this.

Perhaps something along these lines will give you a direction to follow:

{tMin, tMax} = MinMax[ T[[All, 3]]]

T[[All, 3]] = (T[[All, 3]] - tMin) (tMax - tMin)

ListPlot3D[T, ColorFunction -> "TemperatureMap"]
ListContourPlot[T, PlotLegends -> True]