Streamlines (control panel)
The control panel Streamlines is used to adjust parameters of the stream line evaluation.
A streamline shows a trace of a heat flow through any point within the construction. For 2D project traces are produced through several points placed at the surface of selected space.
If there is vapour solution available the flow of vapour diffusion can be visualized with this evaluation alternatively.
The evaluation is performed over the calculated field of heat flux vectors (or vapour diffusion flux vectors) at all nodes of the simulation grid – these fields are available only if evaluation of secondary functions has been chosen (in General the secondary functions is active!). If there is no vector field data available to render the tab will show a tooltip stating that.
The streamline will be calculated over the active vector field by executing the Runge-Kutta method. The streamline (independently from the active function always follows the active vector field) is shown colorized. Only the colorizing of the streamline corresponds to the active function (temperature, heat flux etc.) as set in the General control panel and depends on the colour table selected.
Streamline through one probe point (Slice X/Y/Z)
The position of the starting point to trace the stream is defined by the intersection of the three slice planes Slice-X / Slice-Y / Slice-Z. Impressive visualizations can be obtained also by interactively moving or picking the starting point.
Therefore the slices X,Y,Z provide crucial part of parameters required for this evaluation (but need not be visible nor active).
Streamlines at equidistant intervals of heat stream from space boundary in 2D case
Important: Streamlines are drawn in the plane of slice Z which must be active (even if fully transparent)!
After the option "Start at ... Space Boundary" is selected, the name of the space the streamlines shall be drawn from can be chosen together with the number of intervals the stream of that space boundary shall be divided into. The application calculates the heat (or vapour) stream from/to the space, subdivides it into the given number of equal intervals and draws streamlines at each such calculated start value of the stream function.
This evaluation can be executed for 2D projects or for other project types, but only if the construction is absolutely homogenous in the Z-direction and there are no space connections in this direction also. If this variant of evaluation is actually available can be verified within the streamlines control panel - if the choice option "Start at: Space Boundaries" is inactive (shown greyed) then that type of evaluation is not available in the context of actual simulation results ergo of the actual model.
Remark: Because streamline (the flow) exists in model's interior only it is advisable to either turn the view of the surface completely off or show it partially transparent (i.e. not opaque) or show it as wireframe only. The same applies to the visibility of slice planes X, Y, Z (starting point of stream tracing) which shall be made partly transparent or even completely invisible (Opacity = 0).
Remark: Current implementation of the solution of the initial boundary problem posed here uses Runge-Kutta method of fourth order with adaptive step control. The boundary condition of step control is set to the small, still numerically stable, error value of epsilon = 10-17 and cannot be changed by the user.
Remark: Not to overwhelm the capacity of today's hardware equipment when combined with tube visualization following restrictions apply and are automatically checked and set:
Remark: Start at – Probe X/Y/Z: The position of staring point of a streamline is defined by the intersection of the three slice planes Slice-X / Slice-Y / Slice-Z. The intersection of the three planes must be within model's interior.
Remark: Start at – Space Boundary: Produces many streamlines started at selected space boundary. The application calculates the sum of stream flowing to the space and the sum of stream leaving the space through the boundary (for exterior space, case with two spaces without powers sources one of this values is always 0). The sum with the largest modulus is divided into the number of intervals entered (maximum 200 intervals, i.e. at 0.5% of the heat stream). Along the space boundary the application repeats the calculation of the stream function and places start points for the streamline at interval boundary values calculated earlier (interpolated). To ensure, that every streamline will start each starting point is shifted towards the interior of the model by about the half thickness of the surface fine grind cell (typically 0.5mm or 1mm).
See also: Results 3D window, Active (settings), Opaque and Opacity (setting), Colorize (setting), Solid or Wireframe (setting), General (control panel), Active Function, Isolines (Isotherms), Slice X,Y,Z (control panel), Surface (control panel), Vectors (HedgeHog, Arrows) (control panel)