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Fog on the automotive windshield interferes with the sight of the driver and causes serious safety problems; thus, removing it rapidly has been a longstanding goal in the automobile industry. In this study, we propose a novel method for improving the defogging performance of the defroster without its structural alteration by using vortex generators (VGs). To optimize the performance of the VGs, we performed particle image velocimetry experiments, an evaporation measurement experiment, and a numerical simulation for visualizing the airflow from the defroster inlet. The dimensions of the VG (height h = δ and length ℓ = 5δ) were selected according to the boundary-layer thickness, δ, of the lowest-flow rate (ulow = 0.33 m/s) used in the defroster inlet. We employed a dimensionless parameter, i.e., the secondary flow intensity (Se), to quantify the intensity of vortices for several angles of attack (30°, 45°, and 60°). The results indicated that the vortices generated from VGs with a 30° angle of attack retained their maximum intensity until they reached the vision area of the driver. Additionally, we explored two different configurations of VGs—co-rotating and counter-rotating—and concluded that the counter-rotating configuration had higher performance than the co-rotating configuration. The optimized VGs were directly inserted in the defroster inlet and improved the defogging performance by approximately 10%. The proposed method is applicable to various automobile models for enhancing the performance of the defroster regardless of the interior volume, air-ventilation performance, and other conditions, such as the number of passengers and outside temperature. [ABSTRACT FROM AUTHOR]

Recently, thin‐film assembly at the liquid–air interface has been widely studied. These film scaffolds have high potential to control the crystallization process and fabricate single crystals. However, there have been limitations in understanding and controlling the behavior of polymer chains form into films. This study investigates thin‐film assembly at the hydrogel droplet interface with internal flow and its role. During the hydrogel film formation, the internal flow of the droplet is visualized using micro‐particle image velocimetry technique at various temperatures. From the droplet evaporation, convection flow induced by heat cause buoyancy effect and pressure on the interface film from evaporation flux affect the film morphology and its mechanical characteristics. Therefore, more dense assembled film is generated on the droplet interface. It is expected that the investigations could give better understanding of interface film assembly and controlling its properties. Hydrogel film assembly becomes denser and shows higher mechanical properties with controlling the evaporation at droplet air–liquid interface. Change of its nanoscaffold structures is measured with X‐ray diffraction scans and images are visualized by scanning electron microscopy. Further, internal flow inside the droplet during evaporation process is visualized with particle image velocimetry to analyze the effect at interface film assembly. [ABSTRACT FROM AUTHOR]