Units used in Chaste

Cardiac Units

Note: F=Farad, S=Siemen=Amp/Volt, A=Ampere, u=micro (ie mu).

Quantity	Units	Notes
Length	cm	hence surface-area-to-volume ratio is cm-1 etc
Time	ms
Voltage or intra- or extracellular potential	mV
Capacitance per unit surface area	uF cm-2	Cm, which we refer to as the capacitance, is actually a capacitance per unit area. The SI unit
		of capicitance is the Farad ( = Coulombs/Volts) (C=Q/V)
Conductivities	mS cm-1
(Stimulus) currents per unit volume	uA cm-3	Applies to (intracellular) stimulus currents given to cells in mono/bidomain problems
		(ie a stimulus current as a RHS source term in the bidomain equations. Note we don't allow
		RHS extracellular stimuli)
Currents per unit area	uA cm-2	Applies to all ionic currents (single-cell/mono/bidomain equations), intracellular stimuli
		in single-cell problems or applied as Neumann boundary conditions, and extracellular
		stimuli through electrodes (which are also Neumann boundary conditions)

Cell-based

Quantity	Units	Notes
Length	dimensionless	Nondimensionalised by typical cell diameter (approx 10-5 m)
Time	hours

Mechanics

Material laws parameters, pressures, and active stresses (in cardiac electro-mechanics) are in kPa. For mechanics simulations the user is free to choose the units for all other quantities, but should do so consistently. For example, if gravity is applied, then [density * gravitational acceleration] should be equal kPa/[length] (here [] denotes "units of"), since the governing equations state that divergence of stress summed with density times gravitational acceleration is zero.