A temperature-concentration dependent surface fit for the relative viscosity of a urea-water-solution (UWS) is calculated based on experimental and literature data. For the surface fit, a 2D Lorenzian function was used, where the xaxis was assigned to a urea mass fraction and the y-axis to the solution temperature and the rest of the parameters were optimized based on the experimental and literature data. The surface model describes the relative viscosity of undersaturated urea-water-solution (UWS). The experimental data for the kinematic viscosity was measured with an Ubbelohde capillary viscometer whose temperature was controlled with a thermostat. The temperature and concentration range was from 293.15 to 353.15 K in 10 K increments and for urea mass fractions from 0.325 to 0.7. The kinematic viscosity values from the experiment were converted to relative viscosity by calculating the density of the UWS. An exponential fit was calculated to describe the specific gravity of the UWS based on literature data. Additionally, the surface tension of the UWS was measured at room temperature (293.15 K) in a mass fraction range from 0.302 to 0.596. As a result, simple models describing UWS properties were obtained and these models can be implemented into computational fluid dynamics (CFD) simulations.

This paper opens up the history of structural analysis and dynamics simulations of Wärtsilä engines. It cites already published articles and theses with some backgrounds information. It also discusses some of the backgrounds of the in-house tool development. Additionally, this paper presents the development of the computers and investment of the simulation capacity in order to understand how it has been the enabler of ever more complicated models. It lists the work done during fifty decades. The authors sincerely attempt to make this article as reader-friendly as possible, even though there are over 220 references, which of course demonstrates how dedicated Wärtsilä has been in supporting numerical simulations research in the past fivedecades.

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T his paper describes the simulation-driven design process used in engines technology. The research question is "how to use research in the structural analysis and dynamics field to ensure world-class product development?" This paper describes research on simulation methodologies from the design process perspective, demonstrating the need for research in various steps of product development. Each section of the paper includes one or two practical examples in which research was needed to increase product design quality. In the product definition section, the Digital Design Platform (DDP) shows the coupling between product requirements and simulation tasks. At the concept design stage, it is shown that computational methods can optimize the placement of material in the case of the main bearing cap topology. The second example is JuliaFEM, an open-source finite element method (FEM) platform, which is suitable for heavy-duty method development, where the internals of the FE solver is needed to make new calculation methodologies available. The next section is about detailed design, where an example of an oil sump welds fatigue illustrates the continuous improvement of the simulation methodology. The second example is connecting rod fretting calculation, which illustrates the full complexity of the structural analysis and dynamics simulations. The second last process step is the virtual validation, where first the cylinder head simulation methodology shows the internal connections between different disciplines' simulations. Another example here is the crankshaft virtual validation process, which describes the complexity of the "simple" component calculation as well as illustrates the number of needed competencies. Finally, in the validation process step, Big Data analyses describe the internals and complexity of the methodologies. Lastly, counterweight measurement device development illustrates that validation of the simulation models and methods sometimes leads toward a measurement device development project. As a conclusion, all the previous methodologies are used to build the Wärtsilä 31 engine, which is the most efficient four-stroke engine in the world. It is, of course, a performance achievement, but a lot of research in simulation methodologies, as explained, was needed to make a reliable product with such a high cylinder peak pressure.