Purpose: Active anterior rhinomanometry (AAR) and computed tomography (CT) are standardized methods for the evaluation of nasal obstruction. Recent attempts to correlate AAR with CT-based computational fluid dynamics (CFD) have been controversial. We aimed to investigate this correlation and agreement based on an in-house developed procedure. Methods: In a pilot study, we retrospectively examined five subjects scheduled for septoplasty, along with preoperative digital volume tomography and AAR. The simulation was performed with Sailfish CFD, a lattice Boltzmann code. We examined the correlation and agreement of pressure derived from AAR (RhinoPress) and simulation (SimPress) and these of resistance during inspiration by 150 Pa pressure drop derived from AAR (RhinoRes150) and simulation (SimRes150). For investigation of correlation between pressures and between resistances, a univariate analysis of variance and a Pearson’s correlation were performed, respectively. For investigation of agreement, the Bland–Altman method was used. Results: The correlation coefficient between RhinoPress and SimPress was r = 0.93 (p < 0.001). RhinoPress was similar to SimPress in the less obstructed nasal side and two times greater than SimPress in the more obstructed nasal side. A moderate correlation was found between RhinoRes150 and SimRes150 (r = 0.65; p = 0.041). Conclusion: The simulation of rhinomanometry pressure by CT-based CFD seems more feasible with the lattice Boltzmann code in the less obstructed nasal side. In the more obstructed nasal side, error rates of up to 100% were encountered. Our results imply that the pressure and resistance derived from CT-based CFD and AAR were similar, yet not same.

The dewatering of substrates is one of the key tasks in the handling of material flows in a circular economy. Besides belt filters, sedimenters, and decanters, screw presses are frequently used to reduce the water content of substrates. However, screw presses available on the market are usually designed for high throughputs (>5 m³/h). The dewatering of smaller feed rates (<1 m³/h), however, requires more compact solutions. For this reason, a compact screw press (short screw length), which is normally used in agriculture for cow manure dewatering, was investigated in this work, as there exist no publications on this type of compact screw press. A mobile test setup was developed and loaded with different material such as digested sludge from a wastewater treatment plant, commercially available potting soil, wood shavings, and biological waste. The dry matter content of the feed material, the feed material itself, the screw rotational speed, and the weight setting (pressure) at the back plate were varied, and the effects on the dewatering result were recorded. A significant influence on the dewatering result was found for the weight setting, the type of substrate (particle size), and the dry substance content of the feed material. The tests confirmed that the compact screw press separator is suitable for the dewatering of wood shavings and biological waste (with an increase in dry matter percentage of up to 7.7%). The direct dewatering of potting soil and digested sludge is not possible and can only be implemented by using structural support material. This study fills the gap between published work on large screw presses and potentially new application fields of compact screw press manure separators, which, until now, have only been used in agriculture.

Purpose: State-of-the-art medical examination techniques (e.g., rhinomanometry and endoscopy) do not always lead to satisfactory postoperative outcome. A fully automatized optimization tool based on patient computer tomography (CT) data to calculate local pressure gradient regions to reshape pathological nasal cavity geometry is proposed. Methods: Five anonymous pre- and postoperative CT datasets with nasal septum deviations were used to simulate the airflow through the nasal cavity with lattice Boltzmann (LB) simulations. Pressure gradient regions were detected by a streamline analysis. After shape optimization, the volumetric difference between the two shapes of the nasal cavity yields the estimated resection volume. Results: At LB rhinomanometry boundary conditions (bilateral flow rate of 600 ml/s), the preliminary study shows a critical pressure gradient of −1.1 Pa/mm as optimization criterion. The maximum coronal airflow ΔA := cross-section ratio $$\frac{\mathrm{virtual surgery }}{\mathrm{post}-\mathrm{surgery}}$$virtual surgery post - surgery found close to the nostrils is 1.15. For the patients a pressure drop ratio ΔΠ := (pre-surgery − virtual surgery)/(pre-surgery − post-surgery) between nostril and nasopharynx of 1.25, 1.72, −1.85, 0.79 and 1.02 is calculated. Conclusions: LB fluid mechanics optimization of the nasal cavity can yield results similar to surgery for air-flow cross section and pressure drop between nostril and nasopharynx. The optimization is numerically stable in all five cases of the presented study. A limitation of this study is that anatomical constraints (e.g. mucosa) have not been considered.