Flow-induced hemolysis is a crucial issue for many biomedical applications; in particular, it is an essential issue for the development of blood-transporting devices such as left ventricular assist devices, and other types of blood pumps. In order to estimate red blood cell (RBC) damage in blood flows, many models have been proposed in the past. Most models have been validated by their respective authors. However, the accuracy and the validity range of these models remains unclear. In this work, the most established hemolysis models compatible with computational fluid dynamics of full-scale devices are described and assessed by comparing two selected reference experiments: a simple rheometric flow and a more complex hemodialytic flow through a needle. The quantitative comparisons show very large deviations concerning hemolysis predictions, depending on the model and model parameter. In light of the current results, two simple power-law models deliver the best compromise between computational efficiency and obtained accuracy. Finally, hemolysis has been computed in an axial blood pump. The reconstructed geometry of a HeartMate II shows that hemolysis occurs mainly at the tip and leading edge of the rotor blades, as well as at the leading edge of the diffusor vanes.

Inducers show generally a positive influence on the performance of centrifugal pumps in the two-phase regime, since they produce more uniform mixtures and increase the pressure before the impeller. However, the effect is much more pronounced in part-load compared to overload conditions. In this study, the air–water two-phase flow behavior in a pump inducer was numerically investigated. The main objectives were to clarify the effect of the inducer, the effective operating range, and to examine flow mixing. Several flow conditions were studied, covering part-load, optimal, and overload pumping conditions, together with different relevant gas volume fractions (1%, 3%, and 5%). The simulations were performed using a transient setup and a moving-mesh approach. Two-phase air–water interactions were modeled by the volume of fluid (VOF) method. After checking the proper discretization in space and time, the model was validated against experimental results, revealing excellent agreement. The numerical analysis was able to explain different effects of inducers in part-load and overload conditions. Under overload conditions, the flow separates, leading to the generation of axial vortices and to a negative pressure change across the inducer; additionally, the residence time is reduced, hindering mixing. These vortices are intensified as the gas volume fraction increases, reducing further the pressure downstream of the inducer. This is the reason why inducers can mainly be used in part-load and near optimal conditions in order to improve pumping of two-phase flows.

Steam methane reforming processes represent the economically most competitive processes for the production of synthesis gas and hydrogen despite their high energy costs. Although there is a strong need for highly resource-efficient production, literature on the optimal design of reformers remains scarce due to the inherently high complexity of these processes. This contribution addresses design aspects of reformers for the case study of a side-fired reformer. Based on a two-dimensional furnace representation heat transfer and the optimal tube bundle arrangement for a fixed furnace chamber are investigated using simulation-based parametric study with both a lean radiation-based model and a computational fluid dynamics model that enables the consideration of fuel efficiency. Radiative heat transfer prevails in the reformer on the furnace side and inter-tube distances of at least three diameters are optimal within the investigated design space. The line arrangement of reformer tubes is beneficial in terms of total heat transferred, fuel efficiency as well as the homogeneity of the tube surface temperatures. These findings pave the way for further studies such as three-dimensional design aspects.

The design of reciprocating pumps for the chemical industry requires a detailed knowledge of the apparent phenomena such as undesirable pipe pulsation and harmful cavitation. Since the detailed understanding of the entire mechanism is rather limited, emphasis will be put on the verification of a fluid-dynamic cavitation model for reciprocating positive displacement pumps. This model was established by means of particle image velocimetry (PIV) measurements carried out at a repetition rate of 2 kHz. The PIV results indicate that the fluid-dynamic cavitation model corresponds with the physical reality. While common practice dictates that cavitation should be prevented at all times, the proposed model offers a great opportunity for manufacturers to predict a limit for the extent of occurring cavitation.Cavitation is one of the main causes of damage to piping elements and hydraulic machinery. Cavitation itself is the process of nucleation in a liquid when the pressure falls below saturated vapor pressure. Due to different generation and growth mechanisms, depending on the pressure level, the classification of cavitation types is deemed to be useful. Therefore, cavita-

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