High fidelity numerical simulations of ship and sub-marine hydrodynamics

This paper discusses the use of wall-modeled LES and hybrid RANS-LES models for the prediction of ship and submarine flows. Results from applied cases are discussed to il-lustrate the use of these methods for practical problems as well as the differences between methods. The paper then discusses the underlying theories and assumptions of wall-modeled LES and hybrid RANS-LES models. The focus of this presentation is on wall-modeled LES as these methods are theoretically more well-founded than hybrid RANS-LES models. Re-sults from both canonical and building block flows are then presented and discussed in order to provide a more firm and practical foundation for the recommendations for applied use that are provided in the final concluding remarks section

Industrigolv.

This paper deals with cracking in industrial concrete floars. We have restricted us to study two special cases, that is, eraeks developed by the load itself and eraeks due to shrinkage. We have of course also studied the deformation effects of the load. The effect of the load has here been studied thoroughly by two separate methods, Winklerfoundation and the more exact Elastic halfspace theory. We have also studied effects eaused by two separate loads at a distance. The shrinkage is dealt with in accordonance with a paper from Buö (11) who has studied this problem extensivly. Our purpose has been to establish designing aids for this type of pavements. These are quite extensive and are based on the regulations for concrete structures BBK 79

Large Eddy Simulations of Fully-Developed Turbulent Pipe Flows At Moderate-To-High Reynolds Numbers

Despite the high relevance of wall-bounded turbulence for engineering and natural science applications, many aspects of the underlying physics are still unclear. In particular, at high Re close to many real-life scenarios, the true nature of the flow is partially masked by the inability of numerical simulations to resolve all turbulent scales adequately. To overcome this issue, we aim to numerically investigate fully-developed turbulent pipe flows at moderate-to-high Re ($361 \leq Re_\tau \leq 6,000$), employing LES. A grid convergence study, using the WALE subgrid stress model, is presented for $Re_\tau=361$. Additionally, the prediction accuracy of distinct subgrid-scale stress models, such as WALE, SMG, OEEVM, LDKM, and DSEM, is examined using a range of statistical measures. The results infer, as expected, that SMG and OEEVM are too dissipative, whereas WALE, LDKM, and, more surprisingly, DSEM perform rather well compared to experiments and results from DNS. Moreover, LES utilizing WALE are performed and investigated in detail for six different Reynolds numbers in the interval from $Re_\tau = 361$ to $6,000$ with gradually refined grids. These computations allow an insight into what turbulence information is retained when LES with a wall model is applied to such high Reynolds numbers in the limit of a relatively coarse grid. Second-order statistics for all values of $Re_\tau$ exhibited excellent agreement with the DNS data in the outer region. Surprisingly, results also revealed a dramatic deviation from the DNS data in the sub-viscous layer region irrespective of the $Re_\tau$, attributed to the considered scaling for mesh refinement. Overall, the WALE model enabled accurate numerical simulations of high-Reynolds-number wall-bounded flows at a fraction of the cost incurred if the inner layer was temporally and spatially resolved

H2020 STRATOFLY Project: from Europe to Australia in less than 3 hours

As eluded in previous studies, with special reference to those carried out in the European framework, some innovative high-speed aircraft configurations have now the potential to assure an economically viable high-speed aircraft fleet. They make use of unexploited flight routes in the stratosphere, offering a solution to the presently congested flight paths while ensuring a minimum environmental impact in terms of emitted noise and green-house gases, particularly during stratospheric cruise. However, only a dedicated multi-disciplinary integrated design approach could realize this, by considering airframe architectures embedding the propulsion systems as well as meticulously integrating crucial subsystems. In this context, starting from an in-depth investigation of the current status of the activities, the STRATOFLY project has been funded by the European Commission, under the framework of Horizon 2020 plan, with the aim of assessing the potential of this type of high-speed transport vehicle to reach Technology Readiness Level (TRL) 6 by 2035, with respect to key technological, societal and economical aspects. This paper aims at summarizing the main results achieved so far to solve the main issues related to thermal and structural integrity, low-emissions combined propulsion cycles, subsystems design and integration, including smart energy management, environmental aspects impacting climate change, noise emissions and social acceptance, and economic viability accounting for safety and human factors

Towards the use of Large Eddy Simulation in Engineering

This paper aims at reviewing some important aspects of Large Eddy Simulation (LES) as applied to engineering flows. We first summarize the present status of modeling in incompressible, compressible and reacting multi-phase flows, with a view towards the overall formalism instead of the intrinsic details of different subgrid models. Based on the assumed requirements on future LES, expected to handle full-scale flows and reacting flows with detailed chemistry, we discuss some potentially interesting LES methods for the future. These methods are exclusively based on multi-scale modeling, in which simplified equations are solved within each LES cell, instead of semi-empirical modeling based on the resolved flow scales only. After that we outline a few flows studied by LES at FOI, which form the basis for the subsequent discussion of validation and verification, and quality management, being of increasing importance for practical engineering flows. Next we summarize some practical aspects of LES of engineering applications, many of which being crucial to the successful use of LES, and being of increasing importance for engineering flows. Finally, I present my view of the future use of LES in engineering, which is based primarily on the evolutionary use of LES during the last decade in the fields of hydrodynamics and combustion