Climate under Cover
Digital Dynamic Simulation in Plant Bio-Engineering

Mulch and Row Tunnel Models

Mulch and Row Tunnel

This page converts CUC20 and CUC30 into browser-based tools, covering PE mulching and row-tunnel microclimate behavior.

The MATLAB programs are coupled energy and moisture models, so this web version keeps the same state variables and reconstructs the original figures with interactive charts.

MATLAB sources for cuc20.m and cuc30.m are preserved in matlab-source/cuc20-50 for reference.

CUC20

PE mulching and soil temperature

Recreates the cover and soil temperature regime for clear, black, and white PE mulching with latent heat transfer at the soil surface.

CUC20 model diagram

CUC30

Row tunnel with air humidity

Models the coupled cover, inside air, soil surface, and first underground node, together with humidity ratio inside the row tunnel.

CUC30 model diagram

Implementation

Model translation

  • The web page keeps the same state variables and main outputs as the MATLAB examples.
  • Default parameters follow the original example settings for direct comparison.
  • When the equations become numerically unstable, the status line reports it rather than silently drawing empty charts.

Formula Notes

Key heat and moisture relations

  • FWS(T) = 0.622 * PWS(T) / (Patm - PWS(T)) gives saturation humidity ratio, where T is temperature in °C and FWS is in kg/kg.
  • TO = Tavg + TU * sin(ω(clk - 8)) and WO = FWS(TD) define the outdoor temperature and humidity forcing, with ω = 2π / 24, clk in hr, and TD in °C.
  • ITI = [HI(TC - TI) + CA*QH(TO - TI) + HI(TF - TI)] / (CA*AH) and IWI = [RHO*QH(WO - WI) + KM(GSI*WSTF - WI)] / (RHO*AH) are the row-tunnel air-temperature and humidity-ratio rates.
  • TC, TI, and TF are temperatures in °C; WI and WO are humidity ratios in kg/kg; QH is airflow in m³/m²/hr.
  • HI is convection coefficient in W m-2 °C-1, CA is volumetric heat capacity of air in kJ m-3 °C-1, AH is row-tunnel air depth in m, RHO is air density in kg/m³, KM is mass-transfer coefficient in m/hr, GSI is soil evaporation efficiency, and WSTF is saturated humidity ratio at the floor in kg/kg.