Our discussion about odor movement problems continues. Last time we talked about how air moves and concentrates as it moves through doors or other openings. In this segment, we’ll move on to furniture and other such items.
As we discussed last time, the configuration of an item that is in the odor stream plays a major role in how the odor stream is moved, concentrated or modified from its ideal, straight-line movement. Anything in the path of the air carrying the odor will cause a disturbance and create higher and lower concentrated areas that the dog must learn to work through to reach source.
In Figure 1 a simple square shape interrupts airflow. Note that the air stream bends around the edges of the square as it approaches, then moves around the square. The odor then begins to concentrate downstream of the square as shown in Figure 2. This concentration of odor can cause a green dog to hesitate, possibly even momentarily perform its trained final response. The behavior exhibited by the dog when alerting to such an odor concentration as shown in Figure 4 however will be different than what would be exhibited at an odor source. Figure 3 shows how the concentration can also disperse as flow continues. As airflow continues around the square the concentration of odor continually moves.
The dog should continue to search when contacting such shifting concentrations of odor as shown in the above figures. A well-trained dog will do so even if it is in the sitting position. It will continue to move its nose around as it tries to isolate the odor’s exact source. When in the immediate area of the source, a well-trained dog should hold its nose toward the exact spot as it waits for the reward. A dog that contacts a transient odor concentration, will get eventually move away from the area in its effort to locate the source. Getting up and moving, as it continues the search for the odor source should be encouraged and the dog should be verbally praised for doing so.
Figures 4 and 5 show how air can flow around a circle. Note that similar to a square, the air may pass around the circle then form an eddy just down stream. The triangle shown in Figure 6 creates a void down stream where very little odor will gather for some space after air passes over it. The angled rectangle in Figure 7 has an affect similar to the triangle in how it modifies air movement. The rectangle in Figure 8, which is positioned lengthwise and parallel with the direction of the air’s movement, causes a bend in the airflow and again causes the odor to eddy down stream.
Next time, the discussion will continue with how some very common obstructions to airflow, such as freestanding walls or cubicles often found in office areas can present problems for the detector dog.