@misc {42959,
	title = {Under-resolved DNS of turbulent flow in straight and helically coiled pipes},
	howpublished = {FEniCS 2022, San Diego, USA},
	year = {2022},
	publisher = {FEniCS2022},
	abstract = {Oasis\&nbsp;is an open-source Navier-Stokes solver built on FEniCS entirely written in Python. There are other open-source Navier-Stokes solvers available, such as openFOAM, but it is written in low-level programming language C++. One of the advantages of using Oasis over openFOAM is the usage of high-level Python code that enables users to flexibly control the implementation of problems. In addition, Oasis utilizes MPI to ensure high-performance and scalability on parallel clusters. Oasis has been previously verified and validated, but verification and validation is a continuous process that can establish the reliability of the solver when applied to new problems.\&nbsp;\&nbsp;Here, we present two turbulent flow problems that can illustrate flexible implementation of Oasis with fast and accurate performance. First, direct numerical simulation (DNS) of turbulent flow in a straight pipe was carried out for numerical validation, and the results were compared against published DNS data-set. Second, we examined turbulent flow in helically coiled pipes using fully developed turbulent flow from straight pipes as an inlet velocity profile.\&nbsp;In the straight pipe, our quantitative results showed convergence towards the DNS reference data, as the mesh was refined. In the helically coiled pipe, reported for the first time for a numerical model, stabilization of the turbulent flow was observed towards the outlet. Due to the curved path and the centrifugal force, two counter-rotating vortices referred to as Dean vortices were formed on the cross-section of the pipe. These vortices rapidly intensified the dissipation by creating smaller eddies in the flow and hence contributing to stabilizing the flow.\&nbsp;},
	url = {https://fenicsproject.org/fenics-2022/},
	author = {Yamamoto, Kei and Valen-Sendstad, Kristian}
}
