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December 2005: 1. computed anisotropic power spectrum 2. implemented alfvenic (also incompressible) driving [as an option] in addition to the original isotropic incompressible driving 3. implemented damping of velocity component along mean B-field [controlled by a parameter] 4. modified driving normalization and time intervalTo do list: 1. quantify anisotropy (half done) 2. implement 1-directional (inbalanced) Alfvenic driving 3. calculate oscillation frequency 4. implement relative Alfven-fast driving

Common parameters MHD equations: isothermal; sound speed cs=1 initial condition: uniform density rho0=1; uniform B-field in positive z-direction with Alfven speed va=10 driving: new acceleration field is generated every eddy turnover time, a velocity perturbation, dv=accel*(advection time step), is added to the fluid at each fluid update; dv has power spectrum v(k)=k**6 * exp(-4.*(k/kpk)**2) and kpk at half the simulation box size; normalized by an overall constant to give a turbulence velocity around 0.5 plots: The (anisotropic) power spectrums are computed following the method of Cho and Lazarian, and are presented below as log10 contour plots Specific runs 1. n=64, no v-damping, isotropic incompressible driving driving power spectrum (only Alfven mode is shown because the other modes are similar) density power spectrums Alfven mode velocity power spectrums fast mode velocity power spectrums slow mode velocity power spectrums 2. n=64, no v-damping, alfvenic driving driving power spectrums density power spectrums Alfven mode power spectrums fast mode power spectrums slow mode power spectrums 3. n=128, no v-damping, isotropic incompressible driving driving power spectrum (only Alfven mode is shown because other modes are similar) density power spectrums Alfven mode power spectrums fast mode power spectrums slow mode power spectrums 4. n=128, no v-damping, alfvenic driving driving power spectrums density power spectrums (suppressed and very anisotropic) Alfven mode power spectrums fast mode power spectrums slow mode power spectrums (suppressed and very anisotropic)

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