wiki:ChasteGuides/ChasteUnits

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.

Last modified 6 years ago Last modified on Nov 30, 2014, 4:38:09 PM

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