Twelve symbols, eight orientations, monochrome, labels solved into place.
One text block per symbol, on one side of the branch. Your
label is the top line at every orientation; under it the symbol text and the
value are joined by an equals sign at matched size and weight, italic
distinguishing the variable from its units. No colour, which
leaves it free for temperature maps and path highlighting.
Two kinds of subscript. On a resistance it is structural —
R_cond, R_conv, R_rad,
R_contact — set by the library and naming physics. On T, C, P and q
it is identity: you set it, and it defaults to a bare letter.
Every symbol, every 45°
Geometry is placed by transform; text is never rotated.
Free node
A temperature node with no imposed boundary temperature. Its temperature can be supplied or solved from an energy balance.
Fixed node
A boundary held at a specified temperature, such as ambient air or a temperature-controlled surface.
Thermal break
An adiabatic boundary: no heat crosses the boundary.
Phase-change node
A node at the temperature of a phase change, such as melting or boiling. Energy is absorbed or released as latent heat.
Conduction
Resistance to heat conduction through a material. For a uniform plane wall, R = L/(kA).
Convection
Resistance to heat transfer between a surface and a fluid. R = 1/(hA).
Radiation
An equivalent resistance for thermal radiation between surfaces. Its value depends on the surface temperatures.
Contact
Resistance to heat flow across the interface between two contacting surfaces.
Spreading resistance
Resistance caused by heat spreading from a small area into a larger area, or constricting in the reverse direction.
Isothermal link
The effective thermal resistance of a heat pipe or similar two-phase heat transport device.
Unstated mechanism
An equivalent resistance combining several heat-transfer mechanisms, or a resistance whose mechanism is unspecified.
Capacitance
Thermal energy storage per unit temperature change. For a body with constant specific heat, C = mcₚ.
Heat flow, along a path
A specified heat-transfer rate between two nodes. The arrow points from the sending node to the receiving node.
Thermal break, in line
An insulated connection between two nodes. No heat flows through this path.
Ideal joint
An ideal connection with zero thermal resistance. The connected nodes have the same temperature.
Stream, a medium passing through
A flowing material between inlet and outlet nodes. Mass flow rate, specific heat and temperature change determine its sensible energy change.
Dissipation
Power converted to heat at a node, such as electrical resistance heating or friction.
Radiative input
Radiant power absorbed at a node, such as solar radiation.
Heat flow
A specified heat-transfer rate entering or leaving a node.
Heat flux
Heat-transfer rate per unit area entering or leaving a node. Multiplying heat flux by area gives heat-transfer rate.
Region labels — nine slots, inside the enclosure
Check — a branch that is not axis-aligned
Three mechanisms, three angles, four nodes, some elements named and some
left bare. Nothing hand-placed.
Placement rules
One block per symbol, on the upper side, chosen in world space so
it never inverts as the symbol passes vertical.
The offset is solved from the oriented box's support distance,
then refined against a narrowed test box. Searching outward from a guess
overshot at diagonals, because a block's bounding box clips a rotated
symbol's corner long before the glyphs would.
Textures rotate with their box. The texture belongs to the
block.
Boundary symbols mirror rather than rotate past vertical.
Boxes are one size (84 × 32), so a ladder keeps an even
rhythm however many mechanisms appear in it.
Units are fixed:K/W, J/K,
°C, W, W/cm².
These are network symbols. Rectangular regions, control volumes, surfaces and annotations are available separately in the editor. Editor guide.