Zbigniew Walenta, Ph.D., Dr. Habil.

Department of Biosystems and Soft Matter (ZBiMM)
Division of Complex Fluids (PFPZ)
retiree
telephone: (+48) 22 826 12 81 ext.: 446
room: 327
e-mail: zwalenta

Doctoral thesis
1970Struktura fali uderzeniowej poruszającej się wzdłuż płaskiej ścianki w nieruchomym gazie 
supervisor -- Prof. Włodzimierz Prosnak, Ph.D., Dr. Habil., Eng., IPPT PAN
188 
Habilitation thesis
1992Regularne i nieregularne odbicie fali uderzeniowej od skośnie ustawionej płaskiej ścianki 
Supervision of doctoral theses
1.2008-10-30Słowicka Agnieszka  Badanie metodą dynamiki molekularnej powstawania wybranych nanostruktur w emulsjach616
 
2.1997Torecki Paweł  Opływ tępych brył naddźwiękowym strumieniem rozbieżnym gazu rozrzedzonego 

Recent publications
1.Słowicka A.M., Walenta Z.A., Szymański Z., Expansion of a multi-component laser-ablated plume, EUROPEAN PHYSICAL JOURNAL-APPLIED PHYSICS, ISSN: 1286-0042, DOI: 10.1051/epjap/2011110056, Vol.56, pp.11101-p1-8, 2011
Abstract:

The expansion of a plume generated during laser ablation is studied with the Direct Simulation Monte Carlo method. The plume is a mixture of four disparate molecular mass components and expands in vacuum or into ambient gas. The time dependence of deposition rate is studied and the transition from an initial vacuum-like to a diffusion-like regime of expansion in ambient gas is shown. The lack of stoichiometry increases with the ratio of molecular masses of ablated particles and at disparate masses the stoichiometry is seriously affected. Ambient gas worsens the stoichiometry unless it supplies particles compensating the backward and sideward flows of plume constituents.

Keywords:

laser deposition, plume expansion, DSMC

Affiliations:
Słowicka A.M.-IPPT PAN
Walenta Z.A.-IPPT PAN
Szymański Z.-IPPT PAN
2.Kucaba-Piętal A., Walenta Z.A., Peradzyński Z., Molecular dynamics computer simulation of water flows in nanochannels, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 0239-7528, Vol.57, No.1, pp.55-61, 2009
Abstract:

The work presents the results of the simulations of water flows through narrow channels (Poiseuille flows) performed using the molecular dynamics method, for two different channel widths (equal to 5 and 10 diameters of the water molecule) and for two different materials of the channel walls (copper and quartz).
In the simulations, physical properties of the materials and their electrostatic interactions were considered. The obtained results are compared with the analytical solutions for a micropolar fluid flow taking account of the experimentally obtained rheological constants of water.

Keywords:

nanoflows, micropolar fluid, molecular dynamics simulation, nanochannels

Affiliations:
Kucaba-Piętal A.-other affiliation
Walenta Z.A.-IPPT PAN
Peradzyński Z.-IPPT PAN
3.Walenta Z.A., Kucaba-Piętal A., Peradzyński Z., Fluid Flows in narrow channels, JOURNAL OF TECHNICAL PHYSICS, ISSN: 0324-8313, Vol.50, pp.65-70, 2009
4.Słowicka A., Walenta Z.A., Creating thin layers at the contact surface of two nonmixing liquids, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 0239-7528, Vol.55, pp.173-178, 2007
Abstract:

The paper presents the results of numerical simulation of processes aimed at production of nanostructures with the use of oil emulsions in water. The appropriate molecular models of water and oil, as well as the model of the substance which would sediment at the water – oil interface, are looked for. Such substance, after suitable solidification, would become the main component of the produced material. For the described simulations, the Molecular Dynamics method has been used throughout this paper.

Keywords:

thin layers, contact surface, nonmixing liquids

Affiliations:
Słowicka A.-IPPT PAN
Walenta Z.A.-IPPT PAN
5.Słowicka A., Walenta Z.A., Powstawanie nanostruktur w emulsjach, Systems, Vol.11, pp.255-267, 2006
Abstract:

Współczesne technologie materiałowe są jedną z najszybciej rozwijających się dziedzin nauki i techniki. Szczególnie prężnie rozwijaj się nano- i mikrotechnologie. Jedna z takich nowoczesnych nanotechnologii, badana obecnie w kilku europejskich ośrodkach, wykorzystuje efekt gromadzenia się substancji na granicy faz emulsji. Użyta emulsja ma bardzo drobną strukturę nano-kropli oleju w wodzie. Trzecia substancja, dzięki odpowiednim właściwościom molekularnym, osiadając na powierzchni styku faz cieczy pokrywa powierzchnie kropel oleju. Po usunięciu emulsji substancja ta, zachowując strukturę, zostaje utwardzona i tworzy nano-materiał . W prezentowanej technologii emulsja spełnia rolę matrycy, na której powstaje struktura wytwarzanego materiału. Technik rozdrabniania emulsji jest wiele; stosuje się m.in. aparaty miksujące (homogenizatory), które w przepływie ścinającym rozrywają krople oleju na mniejsze lub mikrokanały o podobnym działaniu [2]. Nanomateriały o prezentowanej strukturze będą miały wiele interesujących właściwości, takich jak lekkość, elastyczność czy wytrzymałość mechaniczną, co zapewniają silne oddziaływania międzyatomowe w układzie oraz porowatość substancji. Tworzywa o takiej budowie mogą znaleźć zastosowanie w różnych dziedzinach np. medycynie czy aerodynamice. Celem naszych prac nad omawianą technologią wytwarzania nanomateriałów było stworzenie numerycznego modelu zjawiska powstawania nanostruktur w emulsjach. Ponieważ tak drobne układy wymagają modelowania na poziomie atomowym, do opisu procesów zachodzących w cieczach posłużono się metodą Dynamiki Molekularnej. Bazując na symulacjach numerycznych zbudowano modele molekularne cieczy tworzących emulsję oraz zaproponowano kilka typów substancji, które mogłyby wytworzyć pożądaną warstwę na granicy faz. Zaproponowane modele testowano numerycznie, poszukując kombinacji oddziaływań międzyatomowych zapewniającej powstawanie oczekiwanej nanostruktury

Keywords:

nanostruktury, emulsje, nanomateriały

Affiliations:
Słowicka A.-IPPT PAN
Walenta Z.A.-IPPT PAN
6.Walenta Z.A., Regularne i nieregularne odbicie fali uderzeniowej od skośnie ustawionej płaskiej ścianki, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.13, pp.1-35, 1991
7.Gmurczyk A.S., Tarczyński M., Walenta Z.A., Struktura fali uderzeniowej w mieszaninie gazów szlachetnych, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.60, pp.1-33, 1978
8.Walenta Z.A., Gmurczyk A.S., Harasimowicz W.W., Leśkiewicz E.M., Tarczyński M., Orzeński J., Sałgut K.J., Rura uderzeniowa ZMCiG, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.47, pp.1-25, 1976
9.Walenta Z., Wpływ niejednorodności gazu na proces odbicia fali uderzeniowej, Prace IPPT - IFTR Reports, ISSN: 2299-3657, No.48, pp.1-28, 1976

List of chapters in recent monographs
1.
549
Słowicka A.M., Walenta Z.A., Hoffman J., Chrzanowska J., Mościcki T., 30th International Symposium on Shock Waves 2, rozdział: Structure and Expansion of a Plume Emitted During Laser Ablation of Multicomponent Materials, Springer International Publishing AG 2017, 2, pp.869-873, 2017

Conference papers
1.Walenta Z.A., Słowicka A.M., Extinguishing detonation in pipelines – optimization of the process, ISIS 2016, 22nd International Shock Interaction Symposium, 2016-07-04/07-08, Glasgow (GB), pp.1-5, 2016
Abstract:

The necessity of extinguishing detonation, which may occur in pipelines transporting gaseous fuels, is nowadays a very important technological problem. The standard devices used for it consist of matrices of very narrow channels. Cooling the gas by cold walls of such channels may extinguish the flame and stop detonation. Detonation may also be extinguished if the cross-section of the channel transporting gas increases abruptly at some place. The desired effect may be achieved if the generated rarefaction waves decrease sufficiently the temperature of the flame (Teodorczyk et al. 1988, Cai et al. 2002, Dremin 1999, Walenta et al. 2004). It might be expected, that simultaneous use of both methods – using narrow channels with variable cross-section – should give even better results. Additional profit might come from the fact, that the flow in narrow channels is usually laminar; the abrupt increase of the cross-section would introduce some turbulence and this way enhance cooling by the walls. However, if the cross-section of the channel increases and decreases, the unwanted heating of the gas may occur. To estimate the net esult, which is not obvious, it is necessary to perform suitable simulations and experiments. The present paper is devoted to numerical simulation of the phenomenon.

Keywords:

extinguishing detonation, DSMC

Affiliations:
Walenta Z.A.-IPPT PAN
Słowicka A.M.-IPPT PAN
2.Walenta Z.A., Słowicka A., Structure of shock waves in complex molecular liquids, 29th International Symposium on Shock Waves, 2013-07-14/07-19, Madison (US), pp.1437-1441, 2013
Abstract:

The present paper is a continuation of our earlier work on the
structure of shock waves in dense media. Simple, monoatomic gas, argon, was con
sidered first [1]. It was found, that the shock thickness in dense argon, when re
lated to the mean distance between the molecules (as suggested by P.W. Bridgm
an [2]) decreased with increasing density. To illustrate the dependence of the thickness of the
shock wave on density of the medium, the results for liquid sulfur hexafluoride were
compared with experimental, shock tube results in gas phase at low density.

Keywords:

molecular dynamics simulations, complex liquids, shock waves

Affiliations:
Walenta Z.A.-IPPT PAN
Słowicka A.-IPPT PAN
3.Walenta Z.A., Słowicka A.M., Structure of shock waves in dense gases and liquids - Molecular Dynamics Simulation, 20th International Shock Interaction Symposium, 2012-08-20/08-24, Stockholm (SE), pp.1-4, 2012
Abstract:

In our earlier paper [3] we reported the investigation of the shock structure in dense, monatomic gas - argon. Here we extend our work to dense molecular gases and to liquids. We investigate, in particular, the influence of the electric charges (electric dipoles, quadrupoles etc.) of the molecules on the shock wave structure.

Keywords:

Shock structure, Dense media, Molecular Dynamics

Affiliations:
Walenta Z.A.-IPPT PAN
Słowicka A.M.-IPPT PAN
4.Słowicka A.M., Walenta Z.A., Szymański Z., Structure of the plume emitted during laser ablation of materials, ISSW28, 28th International Symposium on Shock Waves, 2011-07-17/07-22, Manchester (GB), pp.777-782, 2012
Keywords:

laser ablation, plume expansion, DSMC

Affiliations:
Słowicka A.M.-IPPT PAN
Walenta Z.A.-IPPT PAN
Szymański Z.-IPPT PAN
5.Walenta Z.A., Słowicka A.M., Structure of shock waves in dense media, ISSW28, 28th International Symposium on Shock Waves, 2011-07-17/07-22, Manchester (GB), pp.771-776, 2012
Keywords:

shock waves, dense fluids, molecular dynamics simulations

Affiliations:
Walenta Z.A.-IPPT PAN
Słowicka A.M.-IPPT PAN

Conference abstracts
1.Słowicka A., Walenta Z., Szymański Z., Hoffman J., Mościcki T., Structure and expansion of a plume emitted during laser ablation of multi-component materials, ISSW30, 30th International Symposium on Shock Waves, 2015-07-19/07-24, Tel-Aviv (IL), pp.562-571, 2015
Abstract:

Pulsed laser deposition is a method frequently used for creating thin films of various materials on
solid substrates. High energy laser pulse causes evaporation of the target material, forming a
plume which subsequently
expands and moves with high speed from the target. Thin film of the
evaporated material is deposited on the substrate placed at some distance in front of the target.
The behavior of the plume influences both the stoichiometry and homogeneity of the deposit
ed
layer

the final product of the process. Better understanding of the process of expansion of the
plume, variation of its structure as well as deposition of the material itself is therefore very
important and should give us opportunity for better contro
l of formation of the deposited layer.

Keywords:

laser ablation, plume expansion, DSMC

Affiliations:
Słowicka A.-IPPT PAN
Walenta Z.-IPPT PAN
Szymański Z.-IPPT PAN
Hoffman J.-IPPT PAN
Mościcki T.-IPPT PAN
2.Walenta Z.A., Słowicka A.M., Similarity Parameters for Shock Waves in Dense Fluids, ISSW30, 30th International Symposium on Shock Waves, 2015-07-19/07-24, Tel-Aviv (IL), pp.536-537, 2015
Keywords:

shock waves, dense fluids, molecular dynamics simulations

Affiliations:
Walenta Z.A.-IPPT PAN
Słowicka A.M.-IPPT PAN
3.Walenta Z.A., Słowicka A.M., Influence of moments of inertia of molecules on the structure of shocks in molecular liquids, KKNM, 4th National Conference on Nano- and Micromechanics, 2014-07-08/07-10, Wrocław (PL), pp.76, 2014
Keywords:

shock waves, dense media, molecular dynamics symulations

Affiliations:
Walenta Z.A.-IPPT PAN
Słowicka A.M.-IPPT PAN
4.Walenta Z.A., Słowicka A.M., Structure of shock waves in dense gases and liquids - Molecular Dynamics Simulation, III National Conference of Nano and Micromechanics, 2012-07-04/07-06, Warszawa (PL), pp.99-100, 2012
Keywords:

shock waves, dense fluids, molecular dynamics simulations

Affiliations:
Walenta Z.A.-IPPT PAN
Słowicka A.M.-IPPT PAN