<p>We present a three-parameter, self-similar family of steady, axisymmetric, nonrelativistic solutions that unifies the morphology, kinematics, and viscous transport of accretion–ejection flows. The triplet <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\((\alpha ,\beta ,\gamma )\)</EquationSource> </InlineEquation> governs the radial power-law indices of angular velocity, density, and kinematic viscosity, respectively. In the inviscid limit, the geometric index <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\alpha\)</EquationSource> </InlineEquation> continuously organizes the flow topology—from flared, toroidal envelopes (<InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\alpha &lt;2\)</EquationSource> </InlineEquation>) through the cylindrical limit (<InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\alpha =2\)</EquationSource> </InlineEquation>) to collimated, jet-like funnels (<InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\alpha&gt;2\)</EquationSource> </InlineEquation>)—while the stratification index <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(\beta\)</EquationSource> </InlineEquation> controls mass loading and helical pitch. Introducing a scale-free viscosity <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(\nu (r)\propto r^{\gamma }\)</EquationSource> </InlineEquation> preserves separability and yields an analytic viscous correction <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(\propto r^{\gamma -1}\)</EquationSource> </InlineEquation> to the meridional velocities, with amplitude set by a coupling <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(V_{\gamma }\)</EquationSource> </InlineEquation>. This framework provides closed-form expressions for velocity fields, streamlines, and stream surfaces, enabling quantitative morphology diagnostics such as the opening-angle profile <InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(\psi (\theta )\)</EquationSource> </InlineEquation> and contour-based RMSE for direct comparison with simulations or observations. The resulting <InlineEquation ID="IEq11"> <EquationSource Format="TEX">\((\alpha ,\beta ,\gamma )\)</EquationSource> </InlineEquation> atlas defines a transparent analytic baseline for global HD/GRMHD models, clarifies how viscosity tilts self-similar stream surfaces, and offers benchmark solutions for reduced or physics-informed neural network surrogates.</p>

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Self-Similar Morphological Templates for Axisymmetric Accretion–Outflow Structures

  • Cristian G. Bernal,
  • Samuel D. Sales,
  • Carlos A. Galíndez

摘要

We present a three-parameter, self-similar family of steady, axisymmetric, nonrelativistic solutions that unifies the morphology, kinematics, and viscous transport of accretion–ejection flows. The triplet \((\alpha ,\beta ,\gamma )\) governs the radial power-law indices of angular velocity, density, and kinematic viscosity, respectively. In the inviscid limit, the geometric index \(\alpha\) continuously organizes the flow topology—from flared, toroidal envelopes ( \(\alpha <2\) ) through the cylindrical limit ( \(\alpha =2\) ) to collimated, jet-like funnels ( \(\alpha>2\) )—while the stratification index \(\beta\) controls mass loading and helical pitch. Introducing a scale-free viscosity \(\nu (r)\propto r^{\gamma }\) preserves separability and yields an analytic viscous correction \(\propto r^{\gamma -1}\) to the meridional velocities, with amplitude set by a coupling \(V_{\gamma }\) . This framework provides closed-form expressions for velocity fields, streamlines, and stream surfaces, enabling quantitative morphology diagnostics such as the opening-angle profile \(\psi (\theta )\) and contour-based RMSE for direct comparison with simulations or observations. The resulting \((\alpha ,\beta ,\gamma )\) atlas defines a transparent analytic baseline for global HD/GRMHD models, clarifies how viscosity tilts self-similar stream surfaces, and offers benchmark solutions for reduced or physics-informed neural network surrogates.