HUMID ATMOSPHERIC MODULE

[reda]

Hi,

I'm working on a humid atmospheric case with a pollutant release based on the ground.


the pollutant release is humid, Do i need to specify the water content and droplet's number in the ustsma user routine ?

[Brian Angel]

Hello,

If your pollutant contains water droplets and you feel that they will have an impact on the result of your calculation then you will need to specify and model them. For this you will need to undertake a two phase flow calculation using the Lagrangian model available in Code_Saturne. It is advisable to ensure that your two phase flow set-up follows certain constraints that are typically invoked when using a Lagrangian model, e.g. the maximum droplet concentration per cell, etc. If you do need to model the droplets, you will also need to determine if there is heat and/or mass transfer from the droplets to the air (or vice-versa) and how you will account for this in your modelling procedure.

However, if the pollutant does not contain droplets or they can be neglected without impacting the accuracy of the CFD solution, then you could consider using a scalar to model the pollutant and model the variation in fluid density as the air and pollutant mix using an appropriate equation for density in the cs_user_physical_properties routine. If there are large differences in temperature between the pollutant and the air then you might need to consider solving for temperature and perhaps the variation in viscosity and/or Cp and/or thermal conductivity.

Best regards,

Brian Angel.

[reda]

The new module implemented in the saturne V3 (based on the works of Bouzereau 2004 ) transports three variables ( water content, liquid potential temperature and the number of droplets ) , there is no mention of the lagrangian tracking particles.

regards,

[Jacques Fontaine]

Hello,

You should use (and edit) the meteo file to configure the number of droplets (the example file is given with 0 droplet).

Regards,
JF

[reda]

Thank you for your response.