Malls and airports today are sometimes based on different themes, often mimicking a jungle or some natural environment. Waterfalls are an important and aesthetic aspect when mimicing such environments. Although aesthetically pleasing, these indoor waterfalls result in huge load on the HVAC systems due to extensive humidity generation. To counter this problem, it is important to quantify the humidity generated due to the waterfall.
In this project, we simulate a multiphase flow with species transport to simulate an indoor waterfall and the resulting humidity generation.
Water falls from a 13m high inlet and exits the domain through the outlet. The domain is maintained at 25 degree celcius and 50% relative humidity (RH). There are multiple ways to calculate humidity generation highlighted in research literature but in this case, we use a simple humidity rate generation method to calculate the humidity where we calculate the difference in humidity generation between two time intervals within the domain.
The simulation settings are as follows :
Turbulence model: k-omega SST
Multiphase model: VOF
Species transport : Air and water-vapor mixture.
Evaporation condensation : Lee model
Solver: PISO
Inlet: 30 kg/s at 291.05K (wet bulb temperature of water at 25 C and 50% RH)
Phase change: 287.25 K (Saturation temperature of water at 25 C and 50% RH)
Outlet: 0 Pa, mixture backflow with 0.99 mass fraction(for 50% RH)
Results
The image shows the volume fraction of water. Water enters the domain from the top, falls to the bottom and exits the domain from left and right outlets.
The image shows the relative humidity in the domain. It is observed that the relative humidity reaches above 80% in regions near the waterfall at the bottom.
The image shows the temperature in the domain. It is observed that the water vapors create a cooling effect in the region around the waterfall.
The image shows the velocity in the domain. Some research papers report using velocity values near the waterfall to calculate the rate of mass transfer from water to air.