PhD proposal
Numerical simulations of frost events and optimization of the control strategy in a wine-growing area equipped with wind machines : Application to the Quincy vineyard
Research fields :
Numerical Fluid Mechanics / Environmental optimisation
Subject context :
Spring frosts in viticulture damage buds, and in the worst cases lead to their destruction. As global warming advances the phenological stages of plants, they are increasingly confronted with long periods of frost. As a result, the risk of agronomic damage increases, reducing yields and impacting the sector’s economy. In the Centre-Val de Loire region, winegrowers are massively equipping themselves with wind machines (WM) to secure their production : a fan at the top of a mast mixes colder air near the ground with warmer air from the upper parts of the nocturnal thermal inversion layer, raising the air temperature around the vines by a few degrees. Over the past 15 years, the cooperative has equipped itself with a fleet of wind machines, which now numbers 60 units. Despite the experience gained by the winegrowers in using these towers, a number of questions remain as to how to optimize their operation :
- sectorization and short-term forecasting of the risk of frost, to ensure that the right measures are taken;
- and on the operation of the towers alone, in synergy or coupled with a heating system, according to different topographical configurations and weather conditions.
The proposed thesis is part of the European Innovative Project (EIP) OPTITAG, which aims to optimize the use of wind machines by considering economic, environmental, social, and societal aspects through a multidisciplinary approach (agronomy, aerodynamics, acoustics, sociology, economics). It is integrated into a broader strategy to reduce the environmental footprint of wind machines by optimizing their operation, notably through the intelligent and complementary use of different heating sources.
A previous thesis carried out as part of the EIP SICTAG project led to the acquisition of new knowledge on wind machines and the development of numerical modeling tools.
The present thesis aims to extend this knowledge through numerical simulations, answering the many questions raised during the SICTAG project and refining the methods and tools developed.
To date, the scientific literature on the combined use of wind machines and heating systems primarily focus on field measurements, while the application of numerical simulation in this field is still in its infancy, making it both novel and innovative. We propose a research topic that is scientifically innovative and directly relevant to current climate change challenges, with results that are anticipated to be valuable for the viticulture profession.
Objectives :
This study will focus on two research questions :
- How can these heating devices be selected and positioned around a wind machine according to site topography and frost situation to optimize efficiency and environmental impact, particularly the carbon footprint of this tandem ? ;
- and is the continuous airflow from wind machines sufficient and appropriate to maintain the maximum heat produced at bud height ?
To answer these questions about the efficiency of various frost control strategies, plot-scale numerical simulation using the open-source PALM calculation code (https://palm.muk.uni-hannover.de/trac) will be implemented. This numerical model will be driven by field measurements and boundary layer observations using sounding balloons and drones. A parametric and sensitivity study will be carried out, taking into account the power and position of the heating sources, as well as the thrust and rotation speed of the wind machines. This analysis will enable optimum combinations of control methods to be proposed.
Host structures :
The thesis can be carried out either at Weenat in Nantes and/or at the INRAE OPAALE research unit in Rennes (ACTA team). Regular exchanges will take place with the University of Canterbury in New Zealand.
Technical skills:
Fluid mechanics (environmental, numerical), optimization
Profile required:
Knowledge of environmental fluid mechanics, and above all a strong interest in related numerical methods and data processing, are essential to successfully complete this project. The candidate must be able to work independently and show strong initiative. A good command of French and English is essential.
Preferred start date for the thesis:
late 2024/early 2025
Application deadline:
October 1, 2024
Contact :
Dr Clara Châtaignier, Modelisation Engineer Dr Johan Carlier, Research Engineer
Weather Measures, subsidiary of Weenat, Nantes INRAE Rennes, site de Beauregard
Mail : clara.lecap@weenat.com Mail : johan.carlier@inrae.fr
Tel : 06 64 59 79 71 Tel : 02 23 48 21 69