|
|
|
|
|
Definition of Input
Variables to Homeostasis Simulation
The input variables
will include: measurement of physical properties of mound
material and their permeability to respiratory gases;
measurement of ambient conditions within and outside the mound
and nest; quantification of cumulative generation (typically
from 2 million termites in a mature mound) of exhaled
respiratory gases and water vapour, from physical activity, which
add buoyancy to the gases that are known to drive homeostasis
within the structure. There is no prior work in the
simulation of homeostasis as the geometry of the mound
has never before been captured, but there are analytical
models (Darlington,
Korb and Turner, as well as Lüscher
(1961), Collins
(1979) and Wilson) whose input variables have been
carefully measured in mounds. These include: the movement of
methane tracer gases around the structure, the measurement of
CO2 levels at key points within the structure;
measurement of humidity and water vapour levels around the structure; and
most importantly, the effects of external influences such as
thermal cycling of the sun, rain and the effects of wind
movement, at key points which influence the diffusion of
respiratory gases through the walls of the mound. These
data will be assembled, together with new data recorded as
necessary. |
Modelling and Validation of
Homeostasis
The objective of the
simulation will be to demonstrate an equilibrium in which the
temperature and humidity and O2 and CO2
levels within the nest remain within predefined limits
whilst external climatic factors such as temperature,
precipitation and wind speed, are varied within certain
bounds. The finite volume method will be used to construct
quasi-steady models of the heat, mass and momentum transfer
processes within the termite mound to analyse the temperature
distribution and flow of gases within the structure.
Detailed measurements on samples of mound material will be
made to determine key transport properties such as, the
resistance to air flow, thermal conductivity, diffusivity of
respiratory gases, radiative surface emissivity, etc.
Where necessary, the effect of variations, in assumed values
parameters, will be explored through a sensitivity study with
the eventual model. Validation and confirmation of the
robustness of the ultimate model will be carried out with
changes being fed back to refine the
model. |
|
| |
© Copyright Rupert Soar
2004. All Rights Reserved. |
