[Sayantan Biswas]

Hello Everyone,



I'm currently working on passive tracer mixing simulation in air-water system using transient Euler-Euler method. Consider a vessel (an image is attached), water is patched up to a certain height (water domain) and above that air is present (air domain), multiple nozzles are arranged at the bottom of vessel through which air is coming and enhancing the mixing. The flow field (suitable drag model, lift force & turbulent dispersion force) are in reasonably good agreement with experiment (time averaged distribution as well as flow dynamics/ local fluctuation).



Once the flow is established, I'm enabling species transport model and performing passive mixing simulation i.e. no reaction is involved. The tracer material property is exactly same as water, constant mass diffusion co-efficient is considered as 9.1e-9 m2/s. A small region in the water domain at the central zone (few mm below the air-water interface) is patched with tracer mass fraction 1.

Mixture-Template, mixture density: volume weighted mixing law, mixture viscosity is constant as water, mass diffusivity: Multi-component.



As the simulation progress, I'm observing tracer is being distributed to air domain as well (i.e. going above the air-water interface level), also I'm monitoring volume integral of tracer mass fraction over the entire numerical domain, the amount is continuously increasing with time.



How do I make sure, the tracer gets distributed only in water phase and mass of tracer is conserved?


TIA