A New Aerodynamic Parametrization for Real Urban Surfaces

This study conducted large-eddy simulations (LES) of fully developed turbulent flow within and above explicitly resolved buildings in Tokyo and Nagoya, Japan. The more than 100 LES results, each covering a 1,000 $\times $ 1,000 m $^{2}$ area with 2-m resolution, provide a database of the horizontally-averaged turbulent statistics and surface drag corresponding to various urban morphologies. The vertical profiles of horizontally-averaged wind velocity mostly follow a logarithmic law even for districts with high-rise buildings, allowing estimates of aerodynamic parameters such as displacement height and roughness length using the von Karman constant $=$ 0.4. As an alternative derivation of the aerodynamic parameters, a regression of roughness length and variable Karman constant was also attempted, using a displacement height physically determined as the central height of drag action. Although both the regression methods worked, the former gives larger (smaller) values of displacement height (roughness length) by 20–25 % than the latter. The LES database clearly illustrates the essential difference in bulk flow properties between real urban surfaces and simplified arrays. The vertical profiles of horizontally-averaged momentum flux were influenced by the maximum building height and the standard deviation of building height, as well as conventional geometric parameters such as the average building height, frontal area index, and plane area index. On the basis of these investigations, a new aerodynamic parametrization of roughness length and displacement height in terms of the five geometric parameters described above was empirically proposed. The new parametrizations work well for both real urban morphologies and simplified model geometries.     

Thermal expansion of granitoids

The thermal rock properties are particularly important for natural stones whenever a temperature change may occur, which becomes particularly important when different materials are combined on any architectural structure. The thermal expansion of a rock is dependent on the coefficients of the expansion of the individual rock-forming minerals and the rock fabric. A systematic study on 65 different stones, mostly granitoids and others magmatic rocks, most of them are often used as dimensional building stones, was performed. Temperature and moisture are very important parameters in the natural environment. Therefore, the thermal expansion, and in addition the thermohygric expansion on selected examples, was measured. The data were also discussed considering the effect of the mineralogy and the temperature. A modeling approach was introduced to show how the mineralogy and the related single crystal properties affect the thermal properties and how good a simple calculation can help to characterize the measured thermal expansion of a rock. The directional dependence of the thermal expansion was also discussed and explained based on detailed rock fabric measurements. In this study, the bowing of granitoid samples was tested and compared with bowing phenomena of granitoid facade panels. The slabs were cut in different directions and were studied under different conditions of temperatures and water saturation. It could be clearly documented that the temperature and the moisture have a control on the bowing behavior. The implication of our data is that thermal expansion depends greatly on wetting and drying, i.e., the thermal cracking is characterized by the residual strain observed after cooling to room temperature. The sensitivity to the thermal cracking has a significant control on the application in architectural constructions.     

Geochemical and mineralogical composition of black weathering crusts on limestones from seven different European countries

Twenty-seven samples of black weathering crust and host carbonates were studied from seven European countries (Germany, Hungary, Belgium, Czech Republic, France, Italy and Poland) representing 11 different sites. The samples were collected for sites for which long-term air pollution records are available. The mineralogical analyses (XRD, polarizing microscopy, SEM) have shown that despite decreasing SO₂ emissions crust samples are still very rich in gypsum. Further, in all host rock samples gypsum was also detected. Good correlations (R² > 0.9) were also found between water-soluble calcium and gypsum content and between sulphate and gypsum content both for black crusts and host rocks. The black gypsum crusts are four or five times richer in sulphate than the host rock. The conductivity of dissolved crust and host rock samples also shows a positive correlation with gypsum content of the samples. LA-ICP-MS analyses allowed the detection of high Pb-levels in black crusts and a negative shift in lead concentration at the crust/host rock transition. The lead content of the host rock is 2–5 mg/kg, while that of the crust is 3–25 mg/kg in the sample collected from Germany, while in the Belgian sample these values are 2–14 mg/kg and 80–870 mg/kg for the host rock and crust, respectively. The GC–MS technique allowed to detect the PAH content of black crusts and host rocks. The former one contains 0.6–15.6 (102.5) mg/kg, while in the host rock values between 0.2 and 2.4 mg/kg were found. The present study suggests that still large amounts of air pollution-related minerals and organic pollutants are found in the black weathering crusts of European carbonate buildings despite decreasing trends in air pollution.     

Weathering of volcanic tuff rocks caused by moisture expansion

Moisture expansion in natural building stones is considered one of the most important factors affecting their weathering and deterioration. The processes that may be responsible for the expansion under determinate relative humidity (hygric dilatation) and water-saturated conditions (hydric dilatation) are generally attributed to the presence of swellable clay minerals. In contrast to this assumption, our investigations show that moisture expansion also takes place in volcanic tuff building stones almost free from clay minerals. To provide a deeper understanding of the processes, swelling and deterioration were performed on 14 volcanic tuffs used as important building stones of different ages, compositions and weathering stages from Mexico, Germany and Hungary. The investigations undertaken include extensive chemical, petrophysical and fabric analyses. The samples show a wide range of effective porosity, microporosity, capillary water absorption, moisture expansion, and CEC values. High moisture expansion does not seem to depend on clay mineral content alone. We also observed that there is no significant effect on dilatation if clay minerals are present but only form a thin coat on the outer shell of bigger pores. Moreover, we identified a correlation between microporosity, average pore radius and moisture expansion. The investigations highlight the fact that moisture expansion cannot only be attributed to swellable clay minerals, and suggest that the presence and accumulation of micropores and their average radius and distribution play an important role for non-clay associated swelling intensity, which can most probably be attributed to the disjoining pressure.     

Investigation of droplet dynamics in a convective cloud using a Lagrangian cloud model

A precipitating convective cloud is simulated successfully using the Lagrangian cloud model, in which the flow field is simulated by large eddy simulation and the droplets are treated as Lagrangian particles, and the results are analyzed to investigate precipitation initiation and to examine the parameterization of cloud microphysics. It is found that raindrops appear initially near the cloud top, in which strong turbulence and broadened droplet spectrum are induced by the entrainment of dry air, but high liquid–water mixing ratio is maintained within cloud parts because of insufficient mixing. Statistical analysis of the downward vertical velocity of a droplet W reveals that the transition from cloud droplets to raindrops occurs in the range 20 μm < r < 100 μm, while the variation of W depends on turbulence as well as the droplet radius r. The general pattern of the raindrop size distribution is found to be consistent with the Marshall–Palmer distribution. The precipitation flux can be underestimated substantially, if the terminal velocity $w_{\text{s}}$ is used instead of W, but it is not sensitive to the choice of the critical droplet radius dividing cloud drops and raindrops. It is also found that precipitation starts earlier and becomes stronger if the effect of turbulence is included in the collection kernel.     

Abtragung,Transport und Sedimentation in der östlichen Beltsee (Ostsee)

Ohne ZusammenfassungEine ausführliche Darstellung erscheint in Die Küste, Bd. 3, 1955.     

The North-Chilean Coast Range — an example for the development of an active continental margin

Analysis of extended plutons in the Coast Range of North Chile between 25°30′ and 26°35′ led to the recognition of a complex magmatic and structural evolution from the Upper Paleozoic to the Tertiary. The ascension of the intrusive bodies is dictated by deep-seated block tectonics. Generally the chemistry changes from S-type magmas in the Paleozoic to I-type magmas in the Mesozoic and Cainozoic. This is accompanied by a change in the structural geology of the continental margin which we present in six hypothetic phases (Devonian-Tertiary). We are only at the beginning of an encompassing synthesis of the genesis of the Andean orogen.     

Volcanic dykes in the north Chilean Coast Range

Dense swarms of predominantly mafic dykes outcrop in the north Chilean Coast Range. These rocks are not lamprophyres. They mark channelways used by Jurassic-to-Lower Cretaceous extrusives.The dykes can be divided into three groups according to their petrography, major and trace element compositions. Rocks of the oldest group (series I) are essentially andesitic with high Na, K, Fe, Ti, Mn, P, V and low Al and Sr values. The rocks of series II are normal calc-alkaline basalts and andesites, whereas the rocks of series III are rhyodacites with calc-alkaline affinities.It is proposed that the series I dykes are genetically related to a continental fault system, whereas the dykes of series II and III are directly related to the post-Triassic evolution of the Andean active continental margin.

---

Zusammenfassung Die nordchilenische Küstenkordillere wird von einem dichten Netz vorwiegend mafischer Gänge durchzogen. Es sind dies keine Lamprophyre, sondern sie stellen Zufuhrsysteme effusiver Tätigkeit im Zeitraum Jura bis Unterkreide dar.Die Ganggesteine lassen sich petrographisch und aufgrund Haupt- und Spurenelementchemischer Charakteristika in drei Serien einteilen. Die ältere alkaline Serie I zeichnet sich durch erhöhte Na-, K-, Fe-, Ti-, Mn-, P-, V- sowie niedrige Al- und Sr-Gehalte aus. Die Basalte und Andesite der zweiten Serie hingegen zeigen eine normale kalkalkaline Entwicklung, die sich in den Rhyodaziten der dritten Serie fortsetzen dürfte.Während die Magmen der ersten Serie Affinitäten zu Basaltassoziationen kontinentaler Bruchsysteme aufzeigen, sind die kalkalkalinen Zusammensetzungen für die Magmenentwicklung des andinen, aktiven Kontinentalrandes seit dem Jura typisch.

---

Resumen La Cordillera de la Costa en el Norte de Chile es atravesada por una densa red de filones principalmente máficos. No se trata de rocas lamprofidicas sino representan sistemas de conductión de un volcanismo Jurásico/Cretácico Inferior.Basandose en sus caracteristicas petrográficas y geoquímicas las rocas filonianas se pueden dividir en tres series. La serie I, la más antigua, demuestra altas concentraciones de los elementos Na, K, Fe, Ti, Mn, P y V así como bajos contenidos de Al y Sr. Al contrario, las rocas basálticas y andesíticas de la serie II son caracterizadas por un desarollo calco-alcalino normal, lo cual habrá continuado en las rocas riodacíticas de la serie III.Mientras los magmas de la primera serie se pueden comparar con asociaciones basálticas de sistemas de fallas continentales, las series calco-alcalinas, por el contrario, son tipicas para un magmatismo que actuó en el borde continental activo andino desde el Jurásico.

---

- , , . , , . . . — 1 — Na, K, Fe, Mn, P, V . - ; . , - .

---

---

Prof. Dr. W. Zeil zum 65. Geburtstag gewidmet