Dynamics of fluctuations below a stationary bifurcation to electroconvection in the planar nematic liquid crystal N4.
نویسندگان
چکیده
We fitted C(k,tau,epsilon) proportional to exp([-sigma(k,epsilon)tau] to time-correlation functions C(k,tau,epsilon) of structure factors S(k,t,epsilon) of shadowgraph images of fluctuations below a supercritical bifurcation at V(0)=V(c) to electroconvection of a planar nematic liquid crystal in the presence of a voltage V=sqrt[2]V(0)cos((2pift) [k=(p,q) is the wave vector and epsilon identical with V(2)(0)/V(2)(c)-1]. There were stationary oblique (normal) rolls at small (large) f. Fits of a modified Swift-Hohenberg form to sigma(k,epsilon) gave f-dependent critical behavior for the minimum decay rates sigma(0)(epsilon) and the correlation lengths xi(p,q)(epsilon).
منابع مشابه
Deviations from linear theory for fluctuations below the supercritical primary bifurcation to electroconvection
Over two decades ago it was predicted that nonlinear interactions between thermally driven fluctuations in dissipative nonlinear nonequilibrium systems lead to deviations from mean-field theory. Here we report experimental observations of such deviations as a supercritical primary bifurcation is approached. We measured the mean-square director-angle fluctuations below the bi...
متن کاملOrigin of traveling rolls in electroconvection of nematic liquid crystals.
Electroconvection in nematic liquid crystals exhibits a Hopf bifurcation to traveling rolls for a wide parameter range. The model normally used to describe electroconvection fails to predict this. A recent theoretical extension, the weak-electrolyte model, incorporates the dissociation-recombination reaction of the ionic dopant in the sample and does predict a Hopf bifurcation for a range of pa...
متن کاملPatterns of electroconvection in a nematic liquid crystal
We present a survey of pattern formation in electroconvection of the nematic liquid crystal 4-ethyl-2fluoro-4 8-[2-(trans-4-pentylcyclohexyl)-ethyl] biphenyl ~I52! as a function of three control parameters: the applied voltage, applied frequency, and electrical conductivity of the sample. The patterns are dominated by oblique-roll states. Over the lower range of conductivity, the initial transi...
متن کاملThe corkscrew instability of a Fréedericksz domain wall in a nematic liquid crystal
A liquid crystal with slightly positive dielectric anisotropy is investigated in the planar configuration. This system allows for competition between electroconvection and the homogeneous Fréedericksz transition, leading to a rather complicated bifurcation scenario. We report measurements of a novel instability leading to the ‘corkscrew’ pattern. This state is closely connected to the Fréederic...
متن کاملTemporal and spatial properties of fluctuations below a supercritical primary bifurcation to traveling oblique-roll electroconvection.
We present measurements of thermally-induced oblique-roll traveling-wave (TW) fluctuations below the supercritical primary bifurcation to electroconvection (EC) in the nematic liquid crystal 4-ethyl-2-fluoro-4'-[2-(trans-4-pentylcyclohexyl)ethyl]-biphenyl (I52). First we analyze time sequences of one-dimensional shadowgraph images taken parallel to the director to obtain the TW frequency omega ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Physical review letters
دوره 94 8 شماره
صفحات -
تاریخ انتشار 2005