Quasi-stationary Flow Research Articles

Well-posedness and stability for the two-phase periodic quasistationary Stokes flow

The two-phase horizontally periodic quasistationary Stokes flow in \mathbb{R}^{2} , describing the motion of two immiscible fluids with equal viscosities that are separated by a sharp interface, parameterized as the graph of a function f=f(t) , is considered in the general case when both gravity and surface tension effects are included. Using potential theory, the moving boundary problem is formulated as a fully nonlinear and nonlocal parabolic problem for the function f . Based on abstract parabolic theory, it is shown that the problem is well-posed in all subcritical spaces \mathrm{H}^{r}(\mathbb{S}) , with r\in(3/2,2) . Moreover, the stability properties of the flat equilibria are analyzed in dependence on the physical properties of the fluids.

The effect of the design angle of the turbine nozzle outlet of the piston engine boost system on its effectiveness

The article is devoted to the actual problem of insufficient energy efficiency of combined internal combustion engines. One of the directions of its solution, which became the goal of this work, is a reasonable choice of the optimal value of the design angle of installation of nozzles in a radial-axial turbine, taking into account both its effective power and the coefficient of completeness of using the supplied pulse energy. The authors applied a closed-loop model of the combined engine, embedded in a new calculation method, which was divided into conditional blocks. In the first block, the method of indefinite Lagrange multipliers calculates the optimal values of the turbine elements in which the gas moves. In the second block, for a preliminary assessment of the calculated geometrical parameters of the flow path, the turbine characteristics are calculated: an assumption is made about the one-dimensionality and quasi-stationary flow. For calculations, a method for calculating the parameters of a stage at an average radius was used, supplemented by a semi-empirical method for calculating gas energy losses during the movement of the latter from the turbine inlet to the outlet section. In the third block, the efficiency of the turbine was estimated when working together with a piston engine by using a closed model for it. This made it possible to objectively evaluate such characteristics of the turbine as efficiency and power, which are functionally related to the pressure pulse in the exhaust tract, which will make it possible to predict the operational characteristics of the turbine operating in conjunction with the combined engine.

Gas flows generated by pulse-periodic optical breakdown and quiet optical discharge

Quiet optical discharge in high-pressure xenon is visually stable pre-breakdown stage of optical discharge supported by pulse-periodic short-wavelength infrared laser radiation with intensity of the order of 109 W/cm2. Increasing the laser intensity leads to the transition of the quiet discharge into a pulse-periodic optical breakdown. In this study, quasi-stationary directional flows generated by both the quiet discharge and the optical breakdown are observed. The flows and their initial stages under limited number of discharge pulses are visualized by shadow imaging method using a point-like laser-plasma radiation source. It is shown that the gas streams outflow points in a quiet discharge correspond to the positions of the laser radiation intensity local maxima in the focal beam waist with astigmatism complicated by defocusing effect of thermal lens arising in the discharge zone. The pulse-periodic optical breakdown emits a turbulent gas flow toward the laser beam. The beam refraction on density gradients in the turbulent flow causes the breakdown instability from pulse to pulse. It was found that time-average absorption of laser radiation in a quiet discharge is about 3% (also in a pulse), while that in optical breakdown is 15% and higher (from 70% to 100% in a pulse). Laser beam intensity for quiet discharge at pulse repetition rate νp = 20 kHz ranges from 1.3 × 109 to 1.5 × 109 W/cm2. At intensities above 4 × 109 W/cm2 and repetition rates νp > 50–55 kHz, laser breakdowns are observed in each laser pulse with the focal ratio f/d ≤ 7. At f/d = 10.6 and νp > 28 kHz, the quiet discharge does not transit to laser breakdown due to defocusing by the thermal lens induced.

Gas permeability characteristics of granite-manufactured sand concrete and its numerical simulation using NMR-MIP modified method

Natural sand resources are becoming increasingly scarce with the rapid development of infrastructure. Therefore, manufactured sand usage is inevitable. However, the significant differences in granite powder content between manufactured- and natural sand have a remarkable impact on the pore structure and permeability of cement-based materials, which are crucial for material durability. In this work, several granite powder dosages (0–32 %) of granite-manufactured sand were considered for preparing manufactured sand concrete, and a suitable physical filling model was chosen to quantify the material particle filling for characterizing the overall pore-filling effect. Mercury intrusion porosimetry (MIP) and nuclear magnetic resonance (NMR) were used to examine the pore structure of the specimens. The quasi-stationary flow method was used to test the gas permeability of concrete. Finally, a random hierarchical bundle model using the NMR-MIP method is proposed to predict the gas permeability of cementitious materials based on their pore size distribution. The results show that granite-manufactured sand and an appropriate amount (i.e., 8 %) of granite powder can improve the filling effect and anti-permeability performance of concrete. There is a good correlation between the pore structure parameters and gas permeability, where the physico-mathematical relationships can be modeled. The maximum relative difference between the predicted and experimental values of the random tube bundle model was reduced to 30.93 % using the NMR-MIP method compared to 70.87 % with the traditional MIP method.

Effects of stone powder on microstructure of manufactured-sand concrete and its gas permeability

With the development of infrastructure construction, natural sand resources have become increasingly scarce, and the use of manufactured sand has become inevitable. The unique stone powder in manufactured sand could significantly influent the concrete performance. To characterize the stone powder, a physical filling model was used to quantify the particle grading buildup. Isothermal calorimetry and thermogravimetric analysis determined the corresponding chemical activities. Subsequently, non-destructive testing flow methods were designed, referred to as nuclear magnetic resonance (NMR) and hydrostatic balance (HB), to test the pore structure, and a quasi-stationary flow method was used to test the gas permeability of the manufactured sand concrete. Finally, a random hierarchical bundle model using the NMR-HB method was proposed to predict the gas permeability of concrete based on the pore size distribution. The results showed that a moderate amount of stone powder could reduce the heat of hydration, increase the hydration products, improve the filling effect, and decrease gas permeability. A certain fineness of the stone powder could increase the heat of hydration, increase the hydration products, compact the pores from 4.5 to 50 nm, reduce the filling effect, and increase gas permeability. The maximum relative difference between the predicted and experimental gas permeability values of the random tube bundle model was reduced to 34.38 % using the NMR-HB method, whereas this value was 70.87 % using the mercury intrusion porosimetry (MIP) method.

Capillarity-driven Stokes flow: the one-phase problem as small viscosity limit

We consider the quasistationary Stokes flow that describes the motion of a two-dimensional fluid body under the influence of surface tension effects in an unbounded, infinite-bottom geometry. We reformulate the problem as a fully nonlinear parabolic evolution problem for the function that parameterizes the boundary of the fluid with the nonlinearities expressed in terms of singular integrals. We prove well-posedness of the problem in the subcritical Sobolev spaces Hs(R)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H^s(\\mathbb {R})$$\\end{document} up to critical regularity, and establish parabolic smoothing properties for the solutions. Moreover, we identify the problem as the singular limit of the two-phase quasistationary Stokes flow when the viscosity of one of the fluids vanishes.

Численное исследование двухмерного симметричного течения несжимаемой жидкости с зависящей от координат вязкостью между частично неровными плоскостями

The structure of a symmetric two-dimensional unsteady flow between two planes having a periodic step-like irregularity is investigated by numerical methods using the finite element package Freefem++. The kinematic viscosity of the fluid is chosen as typical for turbulent flows, depending on the coordinates as 𝜇 = 𝜇0(𝜂2(𝑥) − 𝑧2), 𝜂(𝑥) = ℎ(𝑥) + 𝛿, where 𝜇0 is the characteristic viscosity, 𝛿 is the roughness, ℎ(𝑥) is the function defining the boundary 𝑧 = 𝜂(𝑥) (profiles of planes mirror-symmetric with respect to 𝑧 = 0), 𝑥, 𝑧 are longitudinal and transverse coordinates along the main flow. In contrast to the usual parabolic profile of the Poiseuille flow between the planes, with the specified choice of viscosity, the flow profile is logarithmic and has a singularity at the boundary of the region, to prevent which the roughness of the boundary is introduced. A distinctive feature of the problem under study is the setting of boundary conditions on an irregular part of the boundary. On plane sections of the boundary, we maintain the usual non-slip conditions for a viscous liquid, but on the irregular part of the boundary we set only the impermeability conditions of the boundary for the liquid (no sticking!). Computational experiment - numerical solution of the Navier-Stokes equations for a viscous incompressible fluid using a modified penalty method, showed that for a wide set of parameters, the structure of the flow described by the initial non-stationary complete problem and the quasi-stationary flow described by the asymptotic model constructed in the presented paper, for which there is an exact solution, are in good agreement - in the non-stationary flow, a stable regular system of vortices is established concentrated near those surface irregularities for which the boundary has a negative curvature (`deepening’of boundary).

Computational and Experimental Modeling in Magnetoplasma Aerodynamics and High-Speed Gas and Plasma Flows (A Review)

This paper provides an overview of modern research on magnetoplasma methods of influencing gas-dynamic and plasma flows. The main physical mechanisms that control the interaction of plasma discharges with gaseous moving media are indicated. The ways of organizing pulsed energy input, characteristic of plasma aerodynamics, are briefly described: linearly stabilized discharge, magnetoplasma compressor, capillary discharge, laser-microwave action, electron beam action, nanosecond surface barrier discharges, pulsed spark discharges, and nanosecond optical discharges. A description of the physical mechanism of heating the gas-plasma flow at high values of electric fields, which are realized in high-current and nanosecond (ultrafast heating) electric discharges, is performed. Methods for magnetoplasma control of the configuration and gas-dynamic characteristics of shock waves arising in front of promising and advanced aircraft (AA) are described. Approaches to the control of quasi-stationary separated flows, laminar–turbulent transitions, and static and dynamic separation of the boundary layer (for large PA angles of attack) are presented.

Evolution of channel flow and Darcy’s law beyond the critical Reynolds number

For incompressible channel flow, there is a critical state, characterized by a critical Reynolds number Rec and a critical wavevector mc along the channel direction, beyond which the channel flow becomes unstable in the linear regime. In this work, we investigate the channel flow beyond the critical state and find the existence of a new fluctuating, quasi-stationary flow that comprises the laminar Poiseuille flow superposed with a counter-flow component, accompanied by vortices and anti-vortices. The net flow rate is reduced by ~ 15% from the linear, laminar regime. Our study is facilitated by the analytical solution of the linearized, incompressible, three-dimensional (3D) Navier–Stokes (NS) equation in the channel geometry, with the Navier boundary condition, alternatively denoted as the hydrodynamic modes (HMs). By using the HMs as the complete mathematical basis for expanding the velocity in the NS equation, the Rec is evaluated to 5-digit accuracy when compared to the well-known Orszag result, without invoking the standard Orr-Sommerfeld equation. Beyond Rec, the analytical solution is indispensable in offering physical insight to those features of the counter-flow component that differs from any of the pressure-driven channel flows. In particular, the counter flow is found to comprise multiple HMs, some with opposite flow direction, that can lead to a net boundary reaction force along the counter-flow direction. The latter is analyzed to be necessary for satisfying Newton’s law. Experimental verification of the predictions is discussed.Graphical

Derivation of acoustical streaming equations for nonlinear and dispersive fluids

The equations of streaming generated by an acoustic mod propagating in a nonlinear dispersive medium (exhibiting absorption and dispersion of phase sound speed) are derived with an arbitrarily shaped incident acoustical field assumed. This field may be periodic or non-periodic. A general dispersion model represented by a convolution operator taking into account relaxation effects was taken into account. Making the assumption of a periodic acoustic field from the general streaming equation.The quasi-stationary flow is driven by a force given by the average value of the dispersion operator with respect to the velocity and acoustic pressure fields. In the spectral representation, it is given by the weighted spectral power density distribution of the acoustic field. The weight of the distribution is the dispersion coefficient - the eigenvalue of the dispersion operator. A new result also reveals the effect of the refractive index deviation on the driving force of streaming. The possibility of generalizing the description of streaming in the simplest case of a non-Newtonian fluid was analyzed. The Reiner-Revlin model of a simple liquid was assumed. It was also noted that the streaming model in the Maxwell liquid is analytically solvable. It was found that asymptotic states of streaming in this model and the Navier-Stokes model are identical.The derivations use new methods different from those used so far. They are based on the separation of nonlinear modes in the momentum transport equation and on the properties of the Gauss-Weierstrass function for the Fick diffusion operator. So far, the method of successive approximations has been used. The consistency of the obtained equations with the assumptions was checked. The obtained formulas generalize the known descriptions of the form of forces driving streaming and extend their application to the case of nonlinear propagation.

Quasi-stationary flow in a channel with a ferrofluid drop, induced by a rotational magnetic field

Quasi-stationary flow in a channel with a ferrofluid drop, induced by a rotational magnetic field

The global atmospheric energy transport analysed by a wavelength-based scale separation

Abstract. The atmosphere transports energy polewards by circulation cells and eddies. To the present day, there has been a knowledge gap regarding the preferred spatial scales and physical mechanisms of eddy energy transport. To fill the gap, we separate the meridional atmospheric energy transport in the ERA5 reanalysis by spatial scales and into quasi-stationary and transient flow patterns and latent and dry components. Baroclinic instability is the major instability mechanism in the transient synoptic scales and is responsible for forming cyclones, anticyclones, and small-scale Rossby waves. At the planetary scales, circulation patterns are often induced by other mechanisms such as flow interaction with orography and land–sea heating contrasts. However, a separation between circulation patterns at the synoptic and planetary scales has yet to be established. We find that both baroclinically induced and transient energy transport is predominantly associated with eddies at wavelengths between 2000 and 8000 km. The maxima in both types of transport occur at wavelengths around 5000 km, in good agreement with linear baroclinic theory. Since these results are independent of latitude, we adapt the scale separation of the energy transport to be based on the wavelength instead of the previously used wavenumber. We define the synoptic transport by the wavelength band between 2000 and 8000 km. We analyse the annual and seasonal mean in the energy transport components and their inter-annual variability. The scale-separated transport components are fairly similar in both hemispheres. Transport by synoptic waves is the largest contributor to extra-tropical energy and moisture transport, mainly of a transient character, and is influenced little by seasonality. In contrast, transport by planetary waves depends highly on the season and has two distinct characteristics. (1) In the extra-tropical winter, planetary waves are important due to a large transport of dry energy. This planetary transport features the largest inter-annual variability of all components and is mainly quasi-stationary in the Northern Hemisphere but transient in its southern counterpart. (2) In the sub-tropical summer, quasi-stationary planetary waves are the most important transport component, mainly due to moisture transport, presumably associated with monsoons. In contrast to transport by planetary and synoptic waves, only a negligible amount of energy is transported by mesoscale eddies (< 2000 km).

Building a mathematical model to prevent hydrate formation in gas pipelines

Development of mathematical models of laminar gas flow in certainty and uncertainty conditions were considered. All factors that influence to character of flow of gas in pipeline and conditions of arising of hydrate inside of pipeline wall are analyzed. Results of analyze were used for development mathematical model of gas flow in pipeline that allow to calculate main parameters of hydrate deposition process. Model of gas flow consist of three non-linear differential equations that can be solved by exist soft wares. Two and three-dimension characteristic obtained, that describe of quantity of hydrate deposited at given process depending on time.
 Besides, the effectiveness of using DELPHI 7 software to determine the preparation of gas for transportation and the hydrates formed during transportation and its prevention based on the results of the application software was discussed. As a result, the change in cross-sectional area of the pipeline of hydrates formed on the inner surface of the pipeline is shown in 3D. Hydrate formation and elimination are visually represented by graphs. The results of theoretical and practical studies of changes in the inner surface of the pipeline depending on temperature and pressure have been identified. All this was investigated during quasi-stationary gas flow in the pipelines and the results were obtained.
 The assumes regarding calculation of parameters of gas flow were determined and necessary recommendations for applying of developed model in different conditions with taking account of temperature and pressure variation and depending on time of hydrate deposition were presented. The diagram of gas-hydrate separation boundary considered for detailed analysis of process

Quantum Current Algebra in Action: Linearization, Integrability of Classical and Factorization of Quantum Nonlinear Dynamical Systems

This review is devoted to the universal algebraic and geometric properties of the non-relativistic quantum current algebra symmetry and to their representations subject to applications in describing geometrical and analytical properties of quantum and classical integrable Hamiltonian systems of theoretical and mathematical physics. The Fock space, the non-relativistic quantum current algebra symmetry and its cyclic representations on separable Hilbert spaces are reviewed and described in detail. The unitary current algebra family of operators and generating functional equations are described. A generating functional method to constructing irreducible current algebra representations is reviewed, and the ergodicity of the corresponding representation Hilbert space measure is mentioned. The algebraic properties of the so called coherent states are also reviewed, generated by cyclic representations of the Heisenberg algebra on Hilbert spaces. Unbelievable and impressive applications of coherent states to the theory of nonlinear dynamical systems on Hilbert spaces are described, along with their linearization and integrability. Moreover, we present a further development of these results within the modern Lie-algebraic approach to nonlinear dynamical systems on Poissonian functional manifolds, which proved to be both unexpected and important for the classification of integrable Hamiltonian flows on Hilbert spaces. The quantum current Lie algebra symmetry properties and their functional representations, interpreted as a universal algebraic structure of symmetries of completely integrable nonlinear dynamical systems of theoretical and mathematical physics on functional manifolds, are analyzed in detail. Based on the current algebra symmetry structure and their functional representations, an effective integrability criterion is formulated for a wide class of completely integrable Hamiltonian systems on functional manifolds. The related algebraic structure of the Poissonian operators and an effective algorithm of their analytical construction are described. The current algebra representations in separable Hilbert spaces and the factorized structure of quantum integrable many-particle Hamiltonian systems are reviewed. The related current algebra-based Hamiltonian reconstruction of the many-particle oscillatory and Calogero–Moser–Sutherland quantum models are reviewed and discussed in detail. The related quasi-classical quantum current algebra density representations and the collective variable approach in equilibrium statistical physics are reviewed. In addition, the classical Wigner type current algebra representation and its application to non-equilibrium classical statistical mechanics are described, and the construction of the Lie–Poisson structure on the phase space of the infinite hierarchy of distribution functions is presented. The related Boltzmann–Bogolubov type kinetic equation for the generating functional of many-particle distribution functions is constructed, and the invariant reduction scheme, compatible with imposed correlation functions constraints, is suggested and analyzed in detail. We also review current algebra functional representations and their geometric structure subject to the analytical description of quasi-stationary hydrodynamic flows and their magneto-hydrodynamic generalizations. A unified geometric description of the ideal idiabatic liquid dynamics is presented, and its Hamiltonian structure is analyzed. A special chapter of the review is devoted to recent results on the description of modified current Lie algebra symmetries on torus and their Lie-algebraic structures, related to integrable so-called heavenly type spatially many-dimensional dynamical systems on functional manifolds.

Growth rate of azimuthal perturbation modes in an ideal annular linear induction pump

This study is aimed at investigating the growth rate of azimuthal perturbation modes in an ideal annular linear induction pump model. The positive growth rate of azimuthal perturbation modes is associated with the unstable behaviour of the annular linear induction pump and is known in the literature as MHD instability characterized by strong low-frequency oscillations of magnetic field, flowrate, and pressure. A linear stability analysis of a height-averaged quasi-stationary main flow in the ideal annular linear induction pump has been conducted, where only temporally evolving azimuthal modes of the axial velocity and magnetic field perturbations were considered. The obtained results predict damped or damped oscillating perturbations in a stable regime as a function of Rm, Rms, N and κm. In the studied parameter range, an amplification of perturbations without oscillations was observed above the instability threshold. It can be concluded that the analysed model of the ideal annular linear induction pump cannot predict experimentally and numerically the observed low frequency oscillations. Figs 4, Refs 17.

Experimental study on gas permeability of cement-based materials

Gas permeability is an important property associated with the durability of cement-based materials. In this study, an experimental method based on applying a quasi-stationary flow is adopted to evaluate the gas permeability of cement-based materials. The results indicate that the intrinsic permeability of dried cement-based materials is affected by the addition of limestone powder, fly ash, and aggregate. The Katz-Thompson equation could predict the intrinsic permeability by using the capillary porosity, average diameter, and pore tortuosity. The intrinsic permeability of partially saturated cement-based materials decreases when the water saturation increases. The Van Genuchten-Mualem model could describe the relative gas permeability of partially saturated cement-based materials, and the model parameters n value between 1 and 2 while m value ranging from 0.64 to 0.69 for cement and mortar. Moreover, the power function relationship between the intrinsic permeability and Klinkenberg constant of cement-based materials has also been corroborated. Finally, a prediction model of gas permeability of cement-based materials under arbitrary water saturation and pressure gradient is proposed.

ИССЛЕДОВАНИЕ ТЕПЛОГИДРАВЛИКИ ИМИТАТОРА РАСПЛАВА СОЛИ ПРИ ТЕЧЕНИИ В КАНАЛЕ В УСЛОВИЯХ НЕОДНОРОДНОГО ОБОГРЕВА

The possibility of using molten salts based on fluorides as a coolant in promising developments in nuclear power systems requires solving several key scientific and technical problems. These problems are associated with development of reliable structural materials and study of thermophysical characteristics of coolant. Solution to the latter problem was constrained by lack of reliable systematic data on physical and chemical properties, specificity of heat transfer processes, and operation technology of promising compositions of fluoride molten salt. In this regard, a comprehensive study, consisting of studying properties of promising fluoride salt melts, as well as creating an experimental base for verification of engineering calculations, is of particular interest for design of reactor facilities. In course of the work, specifics of interaction of electromagnetic forces and buoyancy forces during MHD heat transfer of molten salt, which can manifest itself in the formation of local overheating points or quasi-stationary flow regimes accompanied by low-frequency temperature fluctuations, were experimentally investigated. For first time, dependences of heat transfer coefficients in a stream under influence of a magnetic field in an extended range of operating parameters were experimentally obtained. The results are compared with known patterns and numerical modeling.

Non-stationary rarefied gas flow in a plane channel with a series of oscillating barriers

Present paper is dedicated to the numerical study of transient free-molecular gas flow through the microchannel with a series of barriers, oscillating perpendicular to the axis of the channel. Phases of barriers motion are arranged in a specific way to obtain a “wave-like” motion of barriers system. Time-dependent flow rate pattern is studied for different values of problem parameters — oscillation frequencies, number of barriers, distance between them, pressure drop in the channel. It is obtained that pattern of gas flow rate significantly depends on the ratio of characteristic “wavespeed” of barriers system motion and the thermal speed of molecules. It is shown that frequency of output pulsatile flow may be significantly higher than the frequency of barriers mechanical oscillations, depending on the number of barriers, which can be used in practice for creation of high-frequency pulsatile flows. Similarly to authors previous paper Kosyanchuk, et al. (2017) it was obtained that motion of barriers system can lead to separation of gas mixtures with different molecular masses. In contrast to “quasi-stationary” (time-periodic) flow regime (at times around 100-1000 oscillation periods), it is shown that in transient regime (at times less than 10-100 oscillation periods) separation factor can be significantly higher. Moreover, separation effect in transient regime is observed even for the values of defining parameters, which do not grant separation in quasi-stationary flow regime.

Gasdynamic Flow Control by Ultrafast Local Heating in a Strongly Nonequilibrium Pulsed Plasma

—The paper presents a review of modern works on gasdynamic flow control using a highly nonequilibrium pulsed plasma. The main attention is paid to the effects based on ultrafast (on the nanosecond time scale for atmospheric pressure) local gas heating, since, at present, the main successes in controlling high-speed flows by means of gas discharges are associated with this thermal mechanism. Attention is paid to the physical mechanisms responsible for the interaction of the discharge with gas flows. The first part of the review outlines the most popular approaches for pulsed energy deposition in plasma aerodynamics: nanosecond surface barrier discharges, pulsed spark discharges, and femto- and nanosecond optical discharges. The mechanisms of ultrafast heating of air at high electric fields realized in these discharges, as well as during the decay of the discharge plasma, are analyzed separately. The second part of the review gives numerous examples of plasma-assisted control of gasdynamic flows. It considers control of the configuration of shock waves in front of a supersonic object, control of its trajectory, control of quasi-stationary separated flows and layers, control of a laminar–turbulent transition, and control of static and dynamic separation of the boundary layer at high angles of attack, as well as issues of the operation of plasma actuators in different weather conditions and the use of plasma for the de-icing of a flying object.

Hydrodynamic phenomena in optical discharges in liquids under self-focusing of periodic-pulse laser radiation

Quasi-stationary flows under the effect of focused periodic pulse femtosecond laser radiation were generated and observed in liquid solvents: water, heavy water, alcohols, ketones, chloromethanes. The mechanism inducing directional flows appears to be directional collapse of the gas bubbles produced by multiphoton dissociation in a focused laser beam. Laser pulses of 450 fs length, up to 220 μJ pulse energy at repetition rates up to 10 kHz have induced stationary flows of liquid originated from the laser beam waist directed along or transversely to the beam axis. The streams along the beam axis were observed under low pulse power (10-20 μJ), provided precise lens adjustment. Lens displacement transversely to the beam axis led to splitting beam waist in two astigmatic foci. Both foci generate the streams along the beam axis. Counter directed streams have collided in the gap between foci, forming the flow spreading transversely to the laser beam. The increase of the pulse energy was followed by formation of the filament of self-focusing. Repeating cycles of focusing and defocusing along the filament produced several beam energy dissipation zones, each one generating separate streams along the beam axis. Colliding of the counter directed streams gave rise to complex flow pattern transversely and upward with respect to the beam axis.