Flow periodicity in microchannels with fin arrays: Experimental validation

• Published in: Experimental thermal and fluid science 2024-10, Vol.158, p.111261, Article 111261
• Main Authors: Eneren, Pinar, Vangeffelen, Arthur, Aksoy, Yunus Tansu, Vetrano, Maria Rosaria
• Format: Article
• Language: English
• Subjects: Flow development length; Flow periodicity; Friction factor; Image stitching; Micro-PIV; Microchannel heat sink; Pressure drop
• ISSN: 0894-1777
• DOI: 10.1016/j.expthermflusci.2024.111261

Investigation of the hydrodynamics within microfluidic chips is crucial for cutting-edge integrated liquid cooling systems due to the coupling between the temperature and velocity fields. Therefore, in this experimental work, we examine the spatial periodicity of the laminar velocity fields and pressure drops inside offset strip fin (OSF) and square pin fin (SPF) arrays at Reynolds numbers between 50 and 292 under isothermal conditions. The velocity fields are characterized using the μPIV technique, and an advanced image stitching algorithm is applied to obtain the streamwise velocity fields. These stitched velocity fields serve two key purposes: evaluation of the flow development length and validation of the flow periodicity due to the periodic nature of the fin arrays. The velocity measurements are compared to the DNS results, and the friction factors acquired from pressure drop measurements are accurately predicted by the correlations based on the periodic flow assumption owing to the rapid flow development. For the first time, to the authors’ knowledge, the consistent monotonic decay of flow perturbations is experimentally evidenced to occur via a single exponential mode. Finally, based on our validation, we confirm the feasibility of using the unit-cell approach to significantly reduce the computational costs compared to simulations that resolve the entire geometry. •The spatial periodicity of the laminar velocity fields and pressure drops are examined inside microchannels with periodic fins.•The velocity fields are characterized using the μPIV technique and an advanced image stitching algorithm is applied.•The flow development length is evaluated to assess the extent of the flow periodicity and validate its assumption.•The velocity measurements are compared to the DNS results, and the correlations accurately predict the friction factors.•For the first time, a consistent monotonic decay of flow perturbations is evidenced to occur via a single exponential mode.