kill(all)$

maxima:appendix:fvm,upwind scheme Φ[e],version 1.0 when(u>0,u<0),version 1.0
peter.vlasschaert@gmail.com,04/11/2022

ref :
new:31/10/2022:maxima :  appendix : fvm : Grid generation for CV in 1D,version 1.0

principal (Upwind-scheme)
------------------------------
- one nodal value   : Upstream 

( )   = nodal values
[e]  = interface of CV 
---------------------------
CV = Control Volume

→ Φ[e]  (x-direction,u>0)
------------------------------
u = velocity x-direction

→ → u-flow → → : "pos-direction"

grid : W→w→ (p) →[e]→( E) 

one nodal value   : p

p1a:Φ[e] =Φ[p]

→ Φ[e]  (x-direction,u<0)
------------------------------
u = velocity x-direction

<- <- u-flow <- <- : "neg-direction"

grid : W→w→ (p) →[e]→( E)

one nodal value   : E

p1b:Φ[e] =Φ[E]