ESP-r: computational fluid dynamics
Current capabilities
ESP-r capabilities for detailed air flow and heat transfer predictions via CFD are as follows:
- non-steady, mixed (turbulent, laminar and transitional) flow within one or more gridded (2D/3D) domains
- time step by timestep interaction with the building and network air flow domains (various regimes possible)
- automatic configuration of the CFD domain and thermal model on the basis of an
exploratory simulation at each time step
- multiple contaminate and humidity sources as well as blockages can be included
- particulates (such as flog) can be tracked
- mean age of air assessments supported
The aim of these facilities is to support explorations of the transient interactions
between (traditional) thermophysical and fluid flow domains.
Primary routines
- bsim2cfd.F -(used when bps/dfs conflation is active)
- bs2cfdsb.F - maps building surface temperatures and convection
coefficients to dfs solid boundaries
- trefbc.F - calculates the reference temperature for surface
convection when dfs models surface convection with a convection coefficient
- bs2cfdblk.F - maps building thermal conditions to dfs blockages
- bndaryl.F - imposes boundary conditions (U, W, W, and T) when flow is laminar
- cfcalc.F - controlling routine for solver iteration and display of progress of solution and residuals.
- init.F - initializes solution variables prior to iteration
- props.F - calculates eddy viscosity, density, thermal expansion
coefficient, and energy diffusion coefficient following each iteration.
- calcu.F - calculates coefficients
for U-momentum equation; calls solver to update U solution
- calcv.F calcw.F calcp.F calct.F calcte.F calced.F - same as calcu.F
but for V-momentum (solves for V), W-momentum (solves for W), continuity
equation (solved for P'), energy equation (solves for T), turbulent kinetic
energy equation (solves for k) and dissipation of turbulent kinetic energy
equation (solves for epsilon)
- indbnd.F - sets U, V, W to 0 at
solid boundaries and sets P at air-flow opening - called once prior to iteration
- inout.F - sets T, U, V, W, k,
epsilon at air-flow openings following each iteration
- recres.F - modifies residuals of solution variable if pressure
is fixed in a cell
- cfconv.F - calculates surface convection coefficients based
on dfs solution
- cfdat.F - reads contents of dfs input file
- conc.F - establishes the concentration equation
- lisolv_3.F - equation solver - sweeps forward and backward in
x, y and z directions (lisolv_1.F and lisolv_2.F are old versions,
lisolv_4.F is biconjugate gradient method)
- mfbndr.F - determines dfs air flow
boundary conditions from solution of an air flow network
- mzmrx5.F - controls the bps equation
solver when thermal conflation type 2 is active
- visual.F - generation of flow visualization images
Primary variables
- COMMON/? - work in progress
Issues arising
CFD facilities are in transition from research-class to early consultant
adopters - some practitioners will be able to use the facilities in support
of consulting work.
- manipulation of input data items (autogridding, blockages,
momentum sources, non-orthogonality etc is less well developed
than other ESP-r facilities)
- refinement of conflation techniques (inflow from blockages coupled with
flow network). Current work is focused on increased stability when there
are multiple connections between a CFD domain and a flow network.
- numerics (overrelaxation, blockage boundary conditions, non-orthogonal coordinates
etc)
- results analysis and output (plane scrolling, particle tracking etc)
Last edited April 2005