Induced free surface oscillations in a freely floating visco-elastic liquid sphere imposed to an oscillatory temperature gradient

The response of a visco-elastic liquid sphere in zero-gravity due to a time-wise oscillating temperature gradient applied at the free liquid surface has been determined analytically for a fluctuating axisymmetric temperature field. The amplitudes of the radial and angular velocity distribution as well as the free surface elevation of the liquid drop have been determined as a function of the “reduced” forcing frequency of the temperature and have numerically been evaluated for a quadratic temperature field. It was found, that visco-elasticity as described by the Maxwell model has quite some influence and appears besides the resonance amplitude with increasing relaxation time as additional peaks below and above resonance. It particularly shows inside the drop, indicating a more pronounced elastic behavior of the liquid.     

Response of a viscous liquid layer around a center-core to axial excitation in zero-gravity

The response of a viscous liquid layer around a center-core to axial excitation has been determined analytically. For a simplified analytical treatment the no-slip condition at the top and the bottom of the liquid column had to be abandoned while the normal condition could be satisfied. The free liquid surface elevation, the radial- and axial velocity distribution have been presented for various surface tension parameters σa/ρv³, aspect ratios h/a and at various locations inside and along the liquid bridge as functions of the forcing frequency parameter Ω a²/ν. It could be noticed that due to viscosity the resonance amplitudes are finite and that the lowest resonance is sharply tuned.     

Response of a viscous liquid layer to pitching-and roll-excitation in zero-gravity environment

The response of a viscous liquid layer to pitching- and roll excitation has been determined. For a simplified analytical treatment the no-slip condition at the top and the bottom of the liquid column has been abandoned in the pitching case. The response of the free liquid surface displacement and the velocity distribution has been determined as a function of the reduced frequency ωa²/ν for various surface tension parameters σa/ρv². Due to viscosity the resonance amplitudes are finite and disappear for higher modes and shorter liquid layers. The velocity distribution, effective moment of inertia and effective damping was obtained for the liquid layer in roll excitation.     

Liquid surface oscillations in a viscous liquid column induced by temperature fluctuations

It was found that timewise fluctuating temperature gradients induce, due to the variation of the surface tension, oscillations of the free surface of a liquid column, which may in or close to resonance lead to large amplitudes, able to disingtegrate the liquid system. An analytical solution leading to the magnification functions and their phases is presented for an arbitrary angular temperature field.     

Response of a liquid column to one-sided axial excitation in zero gravity

A finite cylindrical liquid column consisting of incompressible and frictionless liquid is subjected at the upper end to axial harmonic excitation. The liquid system is in a zero-gravity environment and is held together by surface tension, which acts as restoringforce. The response of the system has been determined for the free surface elevation and the velocity distribution. In addition the transient behavior was investigated. Damping has been introduced in the resonance terms. It was found, that the first resonance response is sharply tuned and could easily be missed by a sweeping experiment. The investigation was performed for the preparation of the German-D-2 Spacelab-Mission “LICORE”.     

Velocity distribution due to marangoni effect for angular temperature field along an infinite liquid bridge under weightless condition

Thermal Marangoni convection inside a liquid bridge is analytically determined for a purley angular temperature field at the free surface of the liquid. Radial- and angular velocity components as well as the stream function are presented for arbitrary stationary and time-periodic temperature fields. The case of a simple stationary sinusoidal temperature field has been evaluated numerically.     

High-pressure cylindrical acoustic resonance diffusion measurements of methane in liquid hydrocarbons

A novel cylindrical acoustic resonance method for the measurement of gas diffusion into liquids at high pressures is described. The measurements were per formed in a vertically oriented cylindrical acoustic resonator containing both the liquid solvent and gaseous diffusant while under high-precision isothermal and isobaric control. Individual resonance modes of the liquid column, the gas column, and the two-phase coupled fluid are resolved in the fast Fourier trans form acoustic-resonance spectrum (FFT-ARS). High-resolution acoustic spectra measured at frequent time intervals reveal the changes which accompany the diffusion fusion of gas into the liquid phase. One change, namely, the growth in length of the liquid column, results in a systematic shift to higher frequencies of axial modes in the gas column. The temporal behavior of this moving boundary, together with quantitative measurement of the flow to the gas column required to sustain the constant pressure, permits determination of the gas-into-liquid diffusion coefficient. Diffusion coefficients were determined from the change in frequency as a function of time of axial resonance modes in the gas-phase virtual cylinder as the surface of the underlying liquid phase advanced due to gas absorption. Measurements of the systems methane/n-octane, methane/n-nonane, and methane/n-decane were performed as a function of temperature at a pressure of 250 psia. Comparisons is made to results obtained elsewhere and by other methods but at the same temperatures and pressure.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

Response of an annual cylindrical liquid column in zero-gravity

An annular liquid layer is subjected in a zero-gravity environment to harmonic axial- and pitching excitation. The liquid is treated as frictionless and is held together by free surface tension, which acts as the restoring force. The response of the system has been determined for the free surface elevation and the velocity distribution. It was found, that the first resonance response is sharply tuned and could easily be missed in a sweeping experiment. Damping was introduced in the resonance terms.     

Surface- and interface oscillations of a rotating viscous liquid column of immiscible liquids

The natural damped coupled frequencies of a rotating viscous infinite liquid column with no axial dependency (∂/∂z=0) have been determined. The frequency equation is presented for a single liquid column, an annular liquid column around a rotating rigid center core, two immiscible liquids with a free- and interfacial surface and also for two immiscible liquids in a rigid container. Only the rotating single liquid column was evaluated numerically and exhibited a rather surprising result. It was found that a viscous column is less stable than that consisting of frictionless liquid. In addition it was found that the conjugate complex roots for each mode in the non-rotating case become two complex roots which are no longer conjugate complex and that the purely decaying roots in the non-rotating case turn into complex roots for rotating liquid, exhibiting damped oscillations.     

Response of an annular cylindrical liquid column to various axial excitations in zero-gravity

An annular liquid layer is subjected in a zero-gravity environment to different harmonic axial excitations. The liquid is treated as frictionless and is held together by free surface tension, which acts as the restoring force. The response of the system has been determined for the free surface elevation and the velocity distribution. It was found, that the first resonance response is sharply tuned and could easily be missed in a sweeping experiment. Damping was introduced in the resonance terms.     

Oscillatory thermo capillary convection in a spinning cylindrical liquid bridge under micro-gravity condition

In a viscous liquid column thermocapillary convection arises under the action of an axial temperature gradient. If this temperature gradient is oscillatory it induces surface oscillations and may lead to large amplitudes, if the frequency of the temperature fluctuation is in resonance with that of the liquid column. The response of the liquid column (non-rotating and rotating) has been determined and the effect of changing aspect ratio, Prandtl number, thermal expansion coefficient and rotational speed of the column in the case of steady temperature gradient may deteriorate for fluctuating temperatures, especially, if the fluctuating frequency is in reasonance with one of the lower natural frequencies of the liquid. The streamlines for the rotating and non-rotating liquid bridge are also presented and show the complex morphology of the convectional flow field, which is due to rotation and temperature oscillations of the liquid system.     

Flexoelectric response of a liquid crystal layer with a temperature-induced orientational transition

It has been confirmed that the flexoelectric polarization model can provide an adequate interpretation of the temperature behavior of the electrical response of homeotropically oriented samples of n-methoxybenzylidene-n-butylaniline nematic liquid crystals at twice the excitation frequency. The temperature dependence of samples with different director orientations has been investigated experimentally. Pis’ma Zh. Tekh. Fiz. 23, 19–23 (May 12, 1997)     

Explosive growth of perturbations of the surface of a conducting liquid in an electric field

An analysis is made of the behavior of the free surface of a conducting liquid in an external electric field near the Tonks-Frenkel instability threshold assuming that the incipient wave is one-dimensional. It is shown that the surface dynamics is described by the nonlinear Klein-Gordon equation. This equation is used to formulate criteria for the explosive growth of perturbation amplitudes. Pis’ma Zh. Tekh. Fiz. 25, 65–69 (November 12, 1999)     

Nonstationary heat and mass transfer in evaporative cooling of flowing liquid films

A mathematical model of nonstationary evaporative cooling of a laminar liquid film flowing down a vertical surface in its blowing with a countercurrent steam-air flow has been developed. The problem of heat and mass transfer has been formulated in a conjugate statement. The calculated data on the time change in the temperature and concentration fields in the steam-air flow and the liquid film as well as in the density of the heat flux on the flowing-film surface have been given. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 1, pp. 3–10, January–February, 2006.     

Response of a rotating finite annular liquid layer to axial excitation

A solidly rotating finite annular liquid layer consisting of nonviscous liquid is subjected to axial harmonic excitation in a zerogravity environment. The response of the free liquid surface elevation and the velocity in radial and axial direction have been determined in the elliptic forcing frequency range Ω>2Ω₀ and in the hyperbolic range Ω>2Ω₀ for different diameter ratios.     

Electromagnetic properties of liquid nitrogen nanolayers on the surface of various substances measured in microwave resonator

Parameters of a microwave resonator containing various substances have been measured on cooling to low temperatures in the frequency range of 12–17 GHz. It is established that the resonance frequency and maximum transmitted microwave power of the resonator sharply change at a temperature of −196°C. The observed effect is explained by the appearance of highly conducting layers at the boundary between the adsorbed liquid nitrogen film and solid substrate.     

Development of artificial perturbations in a nonisothermal liquid film

The effect of artificial perturbations on the formation of structures in a water film flowing over a vertical plate with a heater has been experimentally investigated. Attention has been focused on the study of the propagation of nonstationary perturbations in time immediately after their creation on the surface of the liquid film. The fluorescence method has been used to measure the film thickness field. The temperature field on the film surface has been measured by a high-speed infrared scanner. It has been shown that the passage of the wave front after the action of a perturbation system with the “most dangerous” distance between the cylinders leads to a change in the distance between the rivulets. It has been found that the intensity of introduced perturbations (cylinder diameters) and the characteristics of waves flowing to the heater significantly affect the change in the distance between the rivulets. An increase in the amplitude of the waves at the front of propagating perturbation has been detected. The coalescence of the rivulets in the lower part of the heater has been observed. It has been shown that the passage of several wave fronts is necessary for the complete rearrangement of the flow even when the intensity of perturbations is high.     

Natural damped frequencies of a rotating visco-elastic infinitely long column

The natural damped frequencies are determined for a rotating Maxwellian infinitely long liquid column. The influence of the axial wave length, of relaxation time, of the rotational speed as well as that of a surface tension parameter σa/ϱv² has been investigated for axisymmetric (m=0) and asymmetric motion (m≥1). The numerical results are compared with those of Newtonian liquid. Visco-elastic liquid columns exhibit a larger tendency to oscillate.     

Nonlinear dynamics of the free surface of a conducting liquid in an electric field

The nonlinear dynamics of the free surface of an ideal conducting liquid in an external electric field is investigated. It is found that in the absence of gravity and surface tension the equations of the two-dimensional motion of the medium can be solved in the approximation of small angles of inclination of the surface. It is shown that singularities of the square-root type, for which the curvature is infinite but the surface itself remains smooth, can form on the surface of a conducting liquid over a finite time. Pis’ma Zh. Tekh. Fiz. 24, 25–29 (June 26, 1998)     

Electrical conductivity, thermoelectric power and viscosity of liquid Sn-based alloys

Shear viscosity of liquid Sn–Ag, Sn–Cu and Sn–Ag–Cu eutectics from melting temperature up to 1100 K and their electrical conductivity and thermoelectric power up to 850 K have been investigated. The electrical properties of liquid Sn with additions of Fe and Ni have also been studied. It is shown that small amounts of metal admixtures affect noticeably the behavior of the physical properties of liquid Sn.