Purpose The effects of inlet turbulence parameters on the flow pattern in the ventilation of the IEA Annex 20 room were investigated in detail by also considering the effects of the buoyancy approach and iteration number. The flow pattern under the effects of the inlet turbulence intensity (Tu) and the length scale (LS) in a wide range of intervals has been predicted from the solution multiplicity point of view to check the hypothesis of Hancock and Bradshaw. Boussinesq and ideal gas approaches for buoyancy have been used for both converged iteration numbers of 3,000 and 9,000. Design/methodology/approach Buoyant ventilation flow has been considered and the finite volume ANSYS-Fluent code was used to solve the turbulent conservation equations from the solution multiplicity point of view. RNG k-e turbulence model that is validated and the most used by ventilation community has been used in the computations with the enhanced wall treatment. Solution multiplicity is related to the extreme sensitivity on initial conditions and/or system parameters. Both the effects of initial conditions and system parameters on solution multiplicity have been considered. Findings The main flow pattern in the room may be clockwise, counter-clockwise or intermediate cases dependent on the used buoyancy approach and iteration number. The number of intermediate cases in the ideal gas approach is less than the Boussinesq approach for both iteration numbers. In any room ventilation study, turbulence inlet parameters have the same importance as Archimedes number, used software, computational scheme and iteration number. It was found that Tu has an effect on flow patterns not only for low and medium LS values but also for high LS values. Research limitations/implications Only a mixed ventilation scenario has been considered. The current study is related to a turbulent flow regime, and flow is assumed two-dimensional, steady, incompressible and non-isothermal. Inlet turbulence parameters' effects on flow patterns have been investigated for an empty room with a single aspect ratio. Practical implications Understanding of solution multiplicity phenomenon in ventilation applications can be used to prevent multiple steady states that cause undesired thermal comfort conditions. Originality/value There are opposite arguments in the literature about the effect of inlet turbulence conditions on the flow field and flow reversal. The first aim of this study is to investigate the effects of the inlet turbulence parameters on solution multiplicity in detail by considering these controversial points. Furthermore, many of the available studies are restricted to transitional flows. Secondly, as inlet turbulence parameters, Tu and LS values in a wide range have been investigated for the effects on flow pattern to check the hypothesis of Hancock and Bradshaw. Additionally, solution multiplicity has been shown under the fixed Tu and LS values by changing the buoyancy approach and converged iteration numbers as initial conditions.
Bilen et al. (Fri,) studied this question.