Akademik Veri Yönetim Sistemi
Applied Sciences (Switzerland), cilt.16, sa.3, 2026 (SCI-Expanded, Scopus)
Featured Application: The findings of this study are applicable to the design of compact laminar flow systems, such as microreactors, small-scale heat exchangers, and biomedical circulation loops, where inlet velocity profile shaping can be used to control entrance development length and reduce additional pressure losses without affecting the fully developed flow regime. Hydrodynamic development in laminar pipe flow is mostly defined by classical entrance length relations and fully developed friction factor relations. However, in real systems, the inlet velocity profiles are often shaped by upstream components such as bends, contractions, or manifolds, causing them to deviate significantly from the ideal Poiseuille profile. These deviations directly affect both the development length in the entrance region and energy losses. In this study, steady three-dimensional laminar CFD simulations were performed to investigate the effect of three inlet velocity profile shapes, a uniform profile, a parabolic (Poiseuille) profile, and a strongly peaked power-law profile, in a circular pipe over a Reynolds number range of Re = 100–1500. The flow development was quantified using a profile-sensitive deviation metric based on the ratio of the maximum velocity to the local averaged fluid velocity. The results showed that, although, for all modeled cases, the flows reach the same fully developed laminar flow profile, the entrance development length strongly depends on the inlet velocity profile, and this dependence becomes more pronounced as the Reynolds number increases. The parabolic inlet profile evolves toward the Poiseuille profile very rapidly, and the additional entrance loss is minimal. On the other hand, the power-law (n = 7) profile produces the largest entrance distortions, which leads to the longest relaxation distance. Overall, the proposed perspective in this study directly links profile-based flow development with energy loss and provides a basis for shaping entrance conditions in compact laminar flow systems. In addition, an empirical scaling analysis yielded a compact power-law relation linking Ldev/D to the Reynolds number and the inlet profile parameter (Formula presented.).