Using Gradient as boundary condition

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hpftcb
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Using Gradient as boundary condition

#1 Unread post by hpftcb »

Hi all,

I'm trying to use gradient as BC in the following configuration:

LBC(isFsur) == Che Che Che Che ! free-surface
LBC(isUbar) == Gra Gra Gra Gra ! 2D U-momentum
LBC(isVbar) == Gra Gra Gra Gra ! 2D V-momentum
LBC(isUvel) == Gra Gra Gra Gra ! 3D U-momentum
LBC(isVvel) == Gra Gra Gra Gra ! 3D V-momentum
LBC(isMtke) == Gra Gra Gra Gra ! mixing TKE

LBC(isTvar) == RadNud RadNud RadNud RadNud ! temperature
RadNud RadNud RadNud RadNud ! salinity
RadNud RadNud RadNud RadNud ! dye_01
ad_LBC(isFsur) == Che Che Che Che ! free-surface
ad_LBC(isUbar) == Gra Gra Gra Gra ! 2D U-momentum
ad_LBC(isVbar) == Gra Gra Gra Gra ! 2D V-momentum
ad_LBC(isUvel) == Gra Gra Gra Gra ! 3D U-momentum
ad_LBC(isVvel) == Gra Gra Gra Gra ! 3D V-momentum
ad_LBC(isMtke) == Gra Gra Gra Gra ! mixing TKE

ad_LBC(isTvar) == RadNud RadNud RadNud RadNud ! temperature
RadNud RadNud RadNud RadNud ! salinity
RadNud RadNud RadNud RadNud ! dye_01


I'm using this configuration to allow my current information to leave my domain, using grad = 0.
The problem is that the model blows up.
Using the same model, and the same ts, but with radnud BC, as the following, it doesn't blow up:


LBC(isFsur) == Che Che Che Che ! free-surface
LBC(isUbar) == Shc Shc Shc Shc ! 2D U-momentum
LBC(isVbar) == Shc Shc Shc Shc ! 2D V-momentum
LBC(isUvel) == RadNud RadNud RadNud RadNud ! 3D U-momentum
LBC(isVvel) == RadNud RadNud RadNud RadNud ! 3D V-momentum
LBC(isMtke) == Gra Gra Gra Gra ! mixing TKE

LBC(isTvar) == RadNud RadNud RadNud RadNud ! temperature
RadNud RadNud RadNud RadNud ! salinity
RadNud RadNud RadNud RadNud ! dye_01
ad_LBC(isFsur) == Che Che Che Che ! free-surface
ad_LBC(isUbar) == Shc Shc Shc Shc ! 2D U-momentum
ad_LBC(isVbar) == Shc Shc Shc Shc ! 2D V-momentum
ad_LBC(isUvel) == RadNud RadNud RadNud RadNud ! 3D U-momentum
ad_LBC(isVvel) == RadNud RadNud RadNud RadNud ! 3D V-momentum
ad_LBC(isMtke) == Gra Gra Gra Gra ! mixing TKE

ad_LBC(isTvar) == RadNud RadNud RadNud RadNud ! temperature
RadNud RadNud RadNud RadNud ! salinity
RadNud RadNud RadNud RadNud ! dye_01


In the Grad case velocity doesn't reach great velocities, although Courant increases until the model breaks. Does anyone know if I am implementing gradient correctly?

regards in advance,

Fernando Barreto.

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