The paper presents the results of numerical modeling of turbulent flow and heat transfer in the model room with displacement ventilation. The goal of the study is to assess the shape influence of the thermal manikin placed in the room on the computed airflow structure. Three manikin shapes have been considered: a detailed one (close to a human shape) and ones simplified partially and completely. The problem formulation was close to the test conditions of P.V. Nielsen et al. (2003). The RANS approach based on the standard k-ε turbulence model was applied. The study revealed solution sensitivity to the dimension and topology of the mesh used, as well as the solution dependence on the uncertainty of the inlet velocity distribution. The calculated results were shown to agree generally with the experimental data. The simplification of the manikin shape had a significant impact on the local parameter prediction accuracy.