The paper presents the methods and results of numerical modeling of turbulent airflow in a test room based on the vortex-resolving wall-modeled large eddy simulation approach. The room ventilation is provided by a plain air jet at Re = 5233. The jet is supplied from a slit placed at a side wall under the ceiling. The room geometry and airflow parameters correspond to the experimental benchmark test by Nielsen et al. (1978), but with the periodicity boundary conditions in the transverse direction. Calculations were carried out with the ANSYS Fluent software using fine grids consisting of up to 6x10^7 cells. The paper presents detailed analysis of parametric computations aimed at the evaluation of numerical simulation adequacy. In particular, the grid dependency study was performed and the Kolmogorov scale was estimated.