# Analysis of Cavity Corner Geometry Effect on Recirculation Zone Structure
## 1 Introduction
The study showed that the highest Nu corresponded to the longest heat source, and that enhancement of heat transfer led to velocity distribution change in the cavity. Since flow structure and topology in open-type cavities have already been thoroughly investigated, recent studies have focused on the impact of minor geometrical features on flow. [PERSON] and [PERSON] [4] numerically and experimentally investigated flow in an open-type cavity with \(L/h_{1}=3.58\) to reduce pressure oscillations and noise by changing the rear face geometry of the cavity. Experiments were performed alongside two-dimensional numerical simulations with a Mach number of 0.9. The study revealed that softening of flow impact on the rear face leads to smaller pressure variations between the cavity's internal and external flow at the point of flow impact. A similar study was performed by [PERSON] et al. [5] in a channel with an inclined backwards-facing step (BFS) whose inclination varied from 10\({}^{\circ}\) to 90\({}^{\circ}\). Numerical study showed that the recirculation zone length remained constant in the turbulent flow regime at Re above 15,000 when the step angle was increased above 30\({}^{\circ}\). [PERSON] and [PERSON] [6] also studied laminar flow over an inclined step; numerical study showed that recirculation zone length strongly depends on Reynolds number. Yet no significant effect was noticed for step inclination at all angles. Decreased recirculation zone length was achieved by [PERSON] et al. [6] in a study where the distributions of mean flow and turbulence over a single rounded step were explored. Numerical investigation showed a shorter recirculation zone than for a channel with 90\({}^{\circ}\) BFS. [PERSON] et al. [7] showed that the flow topology behind the BFS could also be impacted by increasing the roughness of the step's surface. A thorough experimental investigation was performed by [PERSON] et al. to study the impact of realistic roughness topographies on turbulence, changing the surface of the step from a rough wall to a smooth wall. The study showed that step roughness influences recirculation zone length; secondary vortices were smaller when the surface of the step wall was rough. Measured shear stress suggested that turbulence can be weakened by increasing roughness. A brief literature survey showed that studies of flow topology in open-type cavities are saturated. However, it was noticed that the impact of small geometry changes on flow structure and topology receives more interest nowadays. There are a decent number of studies on the influence of flow over differently shaped steps. Most are performed in channels with BFS or turbulent flow. To the authors' knowledge, there are no studies on flow topology in open-type cavities with rounded steps in laminar flow; therefore, this is a new fundamental interest and brings novelty to this research topic. The physical meaning of this study is to provide fundamental knowledge of the impact of geometry on recirculation zone dynamics, thus granting the necessary expertise for engineering solutions for various practical applications. The main goal of this study is to investigate the influence of rounded cavity corners on the topology and stability of laminar flow. In this study, flow topology was numerically investigated by employing commercially available Ansys Fluent software. Results of numerical simulations were compared to experimental results to ensure the validity of simulations. Since the results agreed acceptably, further simulations were performed with four different geometries to determine the influence of rounded cavity corners on flow topology. For parametric analysis, pressure loss dependency on Re was obtained. Additionally, velocity profiles in x-y and x-z planes were obtained for all investigated channels. Finally, flow stability was investigated by analyzing _Tu_ distribution in the cavities and _Cf_ distribution on the bottom cavity wall.