@article{delgado_2009,  title={Boundary layer thickness of cylinders and plane surfaces immersed in packed beds in alignment with the flow},  volume={26},  ISSN={0104-6632},  url={https://doi.org/10.1590/S0104-66322009000100005},  DOI={10.1590/S0104-66322009000100005},  number={1},  journal={Brazilian Journal of Chemical Engineering},  publisher={Brazilian Society of Chemical Engineering},  author={Delgado, J. M. P. Q.},  year={2009},  month={Jan},  pages={45–52} }