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The formation of single-channel and multiple-channel rivers on large slopes

Misiura K., Czechowski L., Witek P., Bendiukova A.

Geological Quarterly

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2016

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Vol. 60, No. 4

981--989

EN

We investigated the formation of different types of rivers depending on slope, total discharge, and grain size. Calculations were performed using numerical package CCHE2D, developed by the National Center for Computational Hydroscience and Engineering. The model is based on the Navier-Stokes equations for depth-integrated two-dimensional turbulent flow and the three-dimensional convection-diffusion equation of sediment transport. For each model we use the same river geometry, suspended load concentration, and bedload transport rate. We distinguish three types of rivers using two methods for classification (single-channel, multiple-channels and transitional). We found that the trend line for transitional rivers is an increasing function of Q in space (Q, d) and that for large S the number of multichannel rivers decreases.

2

Modelling of small river deltas : the dependence of morphology on grain size and discharge

Witek P., Czechowski L., Misiura K.

Geological Quarterly

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2016

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Vol. 60, No. 4

975--980

EN

We studied the dependence of the morphology of small river deltas on the grain size, the total discharge, and the slope of the deposits. We use Computational Fluid Dynamics (CFD) methods of numerical modelling. For all models we used the same initial geometry of the river valley and a portion of the lake. Our simulations show the expected dependence of the shape of our simulated small deltas on the grain size. Moreover, we find that the final type of delta could be characterized by the average slope in the region close to the delta front.

3

Comparison of Early Evolutions of Mimas and Enceladus

Czechowski L., Witek P.

Acta Geophysica

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2015

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Vol. 63, no. 3

900--921

EN

Thermal history of Mimas and Enceladus is investigated from the beginning of accretion to 400 Myr. The numerical model of convection combined with the parameterized theory is used. The following heat sources are included: short lived and long lived radioactive isotopes, accretion, serpentinization, and phase changes. The heat transfer processes are: conduction, solid state convection, and liquid state convection. We find that temperature of Mimas’ interior was significantly lower than that of Enceladus. If Mimas accreted 1.8 Myr after CAI then the internal melting and differentiation did not occur at all. Comparison of thermal models of Mimas and Enceladus indicates that conditions favorable for the start of tidal heating lasted for a short time (~107 yr) in Mimas and for ~108 yr in Enceladus. This could explain the Mimas-Enceladus paradox. In fact, in view of the chronology based on cometary impact rate, one cannot discard a possibility that also Mimas was for some time active and it has the interior differentiated on porous core and icy mantle.

4

Laboratoryjny model bezprzewodowej sieci pomiarowo-kontrolnej

Maśnicki R., Witek P.

Zeszyty Naukowe Akademii Morskiej w Gdyni

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2010

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nr 66

95-104

PL

W artykule omówiono konfigurację sieci bezprzewodowej ZigBee współpracującej m.in. ze sterownikiem mikroprocesorowym. Opisano zbudowany układ prototypowy urządzenia końcowego sieci ZigBee oraz sposób połączenia z peryferiami. Przedstawiono algorytmy działania modelu.

EN

In this paper the configuration of wireless ZibgBee network co-operating e.g. with microprocessor controller was discussed. The built End-Device prototype unit of ZigBee network as well as the connection method to the peripherals were described. The algorithms of model operation were presented.