Detailed flow development and indicators of transition in a natural convection flow in a vertical channel

Abstract

Transitional natural convection is studied experimentally and numerically • Different transition indicators are defined based on velocity and thermal quantities • Detailed experimental and numerical mapping of the flow spatial development is provided • Realistic environmental conditions are considered Detailed flow development and indicators of transition in a natural convection flow in a vertical channel.

Transitional natural convection flow in a vertical channel: Impact of the external thermal stratification

“…This study is in the continuation of the works of Thebault et al [20,7] in which the configuration studied as well as the experimental and numerical methodologies are introduced in details. For those reasons, only a brief summary is presented here.…”

“…However changes of δ T during one measurement were very small leading to non-appreciable differences of the flow quantities [20]. More details about the experimental measurements as well as the ambient conditions are presented in [20,7]…”

“…[10,28,29]), there are large velocity disturbances at the inlet of the channel that comes from the surrounding environment. These disturbances must be considered to obtain a more realistic numerical model [30,31,7]. To mimic that environmental velocity disturbance, an inlet velocity noise was added at the lower open boundaries of the computational domain using the spectral synthesizer approach [32] which is commonly used in LES methodology [33].…”

“…In these conditions, the hydrostatic pressure, p (Pa) in the thermally stratified far field can be expressed, using the perfect gas law, as [7]…”

“…In a recent paper Thebault et al [7] provided a detailed description of the spatial development of the transitional flow and associated different indicators to different stages of the transition. In the present paper, the effect of the boundary conditions, and more especially the external thermal stratification, on the transitional flow is investigated.…”