Microscale fluid systems are becoming common in many applications ranging from electronic cooling to refrigeration systems and more. Onedimensional numerical models represent a simple and fast tool for the design of such devices, yet they struggle to accurately predict the flow characteristics in compressible microflows. Under the adiabatic assumption, the elegant theory developed by Fanno allows models for the viscous compressible flow in constant crosssection channels to be easily built. Although reasonably accurate, these models suffer from drawbacks inherent to their being onedimensional, as such they cannot take into account the local profiles of quantities like the velocity and the temperature. In cascade, this results into incorrect evaluations of other dependent quantities, such as the dynamic pressure and the fluid thermophysical properties. The mismatch turns large when the fluid compressibility becomes important. As the Mach number grows, the velocity profile changes, and so the friction factor, even though a reliable model for predicting this change is still missing. In fact, a constant friction factor throughout the channel is generally assumed, following the incompressible flow theory. Here, a set of correlations is proposed improving the 1D theory accuracy by taking into account the effects of the nonuniform velocity and temperature profiles in a quasi2D fashion. A detailed analysis of the velocity profiles at different Mach numbers coming from a large set of CFD simulations results in a model for assessing the impact of compressibility on friction and other quantities. The numerical model proposed, being able to properly account for the compressibility effects, offers an improved tool for the design of microscale fluid systems. Extending the analysis to include heat transfer is not difficult as the effect of heat flux will be analogous to the effect of pressure drop due to friction.
Compressible Fanno flows in microchannels: An enhanced quasi2D numerical model for laminar flows / Cavazzuti, Marco; Corticelli, Mauro A.; Karayiannis, Tassos G..  In: THERMAL SCIENCE AND ENGINEERING PROGRESS.  ISSN 24519049.  10:(2019), pp. 1026. [10.1016/j.tsep.2019.01.003]
Compressible Fanno flows in microchannels: An enhanced quasi2D numerical model for laminar flows
Cavazzuti, Marco;Corticelli, Mauro A.;
2019
Abstract
Microscale fluid systems are becoming common in many applications ranging from electronic cooling to refrigeration systems and more. Onedimensional numerical models represent a simple and fast tool for the design of such devices, yet they struggle to accurately predict the flow characteristics in compressible microflows. Under the adiabatic assumption, the elegant theory developed by Fanno allows models for the viscous compressible flow in constant crosssection channels to be easily built. Although reasonably accurate, these models suffer from drawbacks inherent to their being onedimensional, as such they cannot take into account the local profiles of quantities like the velocity and the temperature. In cascade, this results into incorrect evaluations of other dependent quantities, such as the dynamic pressure and the fluid thermophysical properties. The mismatch turns large when the fluid compressibility becomes important. As the Mach number grows, the velocity profile changes, and so the friction factor, even though a reliable model for predicting this change is still missing. In fact, a constant friction factor throughout the channel is generally assumed, following the incompressible flow theory. Here, a set of correlations is proposed improving the 1D theory accuracy by taking into account the effects of the nonuniform velocity and temperature profiles in a quasi2D fashion. A detailed analysis of the velocity profiles at different Mach numbers coming from a large set of CFD simulations results in a model for assessing the impact of compressibility on friction and other quantities. The numerical model proposed, being able to properly account for the compressibility effects, offers an improved tool for the design of microscale fluid systems. Extending the analysis to include heat transfer is not difficult as the effect of heat flux will be analogous to the effect of pressure drop due to friction.File  Dimensione  Formato  

1s2.0S2451904918305456main.pdf
Open access
Tipologia:
Versione pubblicata dall'editore
Dimensione
5.15 MB
Formato
Adobe PDF

5.15 MB  Adobe PDF  Visualizza/Apri 
Pubblicazioni consigliate
I metadati presenti in IRIS UNIMORE sono rilasciati con licenza Creative Commons CC0 1.0 Universal, mentre i file delle pubblicazioni sono rilasciati con licenza Attribuzione 4.0 Internazionale (CC BY 4.0), salvo diversa indicazione.
In caso di violazione di copyright, contattare Supporto Iris