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Torsional motions are ubiquitous in the solar atmosphere. In this work, weperform 3D numerical simulations which mimic a vortex-type photospheric driverwith a Gaussian spatial profile. This driver is implemented to excite MHD wavesin an axially symmetric, 3D magnetic flux tube embedded in a realistic solaratmosphere. The Gaussian width of the driver is varied and the resultingperturbations are compared. Velocity vectors were decomposed into parallel,perpendicular and azimuthal components with respect to pre-defined magneticflux surfaces. These components correspond broadly to the fast, slow and Alfvenmodes, respectively. From these velocities the corresponding wave energy fluxesare calculated, allowing us to estimate the contribution of each mode to theenergy flux. For the narrowest driver ($0.15$ Mm) the parallel componentaccounts for $\sim 55 - 65\%$ of the flux. This contribution increases smoothlywith driver width up to nearly $90\%$ for the widest driver ($0.35$ Mm). Therelative importance of the perpendicular and azimuthal components decrease atsimilar rates. The azimuthal energy flux varied between $\sim 35\%$ for thenarrowest driver and $< 10\%$ for the widest one. Similarly, the perpendicularflux was $\sim 25 - 10\%$. We also demonstrate that the fast mode correspondsto the sausage wave in our simulations. Our results therefore show that thefast sausage wave is easily excited by this driver and that it carries themajority of the energy transported. For this vortex-type driver the Alfven wavedoes not contribute a significant amount of energy.

Varying Driver Velocity Fields in Photospheric MHD Wave Simulations