BLENCV - How to explain clearly this option ?

[Clément Boré]

Hi everybody,

Could someone explain to me, with a plain and pedagogical language if possible, how to explain the BLENCV option (conservative or not scheme I suppose) ?

Thanks helping me,

Clément BORE
Cooling Tower calculator (CTWR)
EDF R&D

[Alexandre Douce]

Hi Clément,

In Code_Saturne you have three spatial discretizations available:  Upwind, Solu and Centered.

In order to choose a scheme,  I propose some recommendations here:
http://code-saturne.org/forum/viewtopic ... =769#p4299

Simply, the BLENCV keyword allows to mix an Upwind scheme with a Centered scheme.  If BLENCV = 0 the scheme is Upwind, if BLENCV = 1, the scheme is Centered.  In most of the cases, you should not have another value for this parameter.  But, if you encounter problems of stability with a Centered scheme, you could try 0.8 for BLENCV in order to stabilize the solution.

[Clément Boré]

Hi Alexandre,

Thanks for your detailed answer.

I sum up the context of my question : To allow us to perform complete calculations on EDF Cooling Tower with Code_Saturne and a specific modeling of our own (AERO), we see that choosing a BLENCV = 0 was more adapted to have good results and stable calculations. We previously experiment difficulties to establish the air flow-rate at the entrance of the tower and inside the tower untill the exit. The flow is lifted up by natural convection without any mechanical help inside the tower. That was the reason why I asked more informations about this "upwind" options.

See your later,

Clément