Computational fluid dynamics analysis of the thermal distribution of animal occupied zones using the jet-drop-distance concept in a mechanically ventilated broiler house

•A jet drop distance model is useful concept to predict the horizontal travelling distance of the cold jet however, experimental approach showed many limitations.•CFD technique was adopted to compute the jet drop distance using user-defined-function.•Validation was conducted through comparative analysis between CFD computed results and experimental results of previous research.•It showed good agreements for designed methodology.•Validated method was applied for analyzing jet drop distance of a broiler house.

Controlling airflow trajectory through slot-openings is important to induce an efficient thermal exchange in a broiler house, particularly in winter. A jet-drop-distance model was proposed to establish a plan for the control and management of a cold jet trajectory by Zhang & Strom (1999), Transactions of the ASAE, 42(4), 1121–1126. Jet-drop-distance is defined as the horizontal distance from a wall to an animal occupied zone where the incoming cold air first reaches at. Regression models employing jet-drop-factor and corrected Archimedes number variables were calculated based on experimental data. However, this approach was restricted, because of the small-scale model, the small number of slot-openings and difficulties in measuring invisible airflows being observed. Here, computational fluid dynamics (CFD) was adopted to overcome the experimental limitations and to analyse jet-drop-distances qualitatively and quantitatively in a commercial broiler house with multiple slot-openings. Predictions of jet-drop-distances were computed using the experimental conditions used by Zhang & Strom (1999) and compared with their regression models to validate the accuracy of developed method. In the validation test, the regression model using the corrected Archimedes number more accurately predicted the jet-drop-distance in the simulation model (R2 = 0.90). The validated method was subsequently applied to the analysis of the jet-drop-distance in a mechanically ventilated broiler house with multiple slot-openings. Trends of the CFD computed jet-drop-distance were analysed according to such variables as ventilation rate, initial angle of slot-openings and outdoor air temperature.